Dosimetric Predictors for Acute Esophagitis during Radiation Therapy for Lung Cancer: An Update of a Large Statewide Observational Study

PURPOSE/OBJECTIVE(S)

Acute esophagitis remains a clinical challenge during the treatment of locally advanced non-small cell lung cancer (NSCLC). Here, we analyze the dosimetric and patient-level characteristics associated with acute grade 2+ and 3+ esophagitis in patients undergoing radiation therapy for NSCLC across a statewide consortium.

MATERIALS/METHODS

Demographic, dosimetric, and acute toxicity data were prospectively collected for patients undergoing definitive radiation therapy +/- chemotherapy for stage II-III NSCLC from 2012-2022 across the Michigan Radiation Oncology Quality Consortium (MROQC). Logistic regression models were used to characterize the risk of grade 2+ and 3+ esophagitis as a function of dosimetric and clinical covariates. Multivariate regression models were fitted to predict the 50% risk of grade 2 esophagitis or 3% risk of grade 3 esophagitis at each dose value.

RESULTS

Of 1760 patients evaluated, 84.2% had stage III disease and 85.3% received concurrent chemotherapy. 79.2% of patients had an ECOG performance status ≤1. Rates of acute grade 2+ and 3+ esophagitis were 48.4% and 2.2%, respectively. On multivariate analyses, performance status, mean esophageal dose and esophageal D2cc were significantly associated with grade 2+ and 3+ esophagitis. Concurrent chemotherapy was associated with grade 2+ but not grade 3+ esophagitis. Dose-response relationships were modeled for grade 2+ and 3+ esophagitis by mean esophageal dose and esophageal D2cc, stratified by performance status and/or receipt of concurrent chemotherapy. For all patients, mean esophageal dose of 29 Gy and esophageal D2cc of 61 Gy corresponded to a 3% risk of acute grade 3+ esophagitis. For patients receiving chemotherapy, mean esophageal dose of 22 Gy and esophageal D2cc of 49.5 Gy corresponded to a 50% risk of acute grade 2+ esophagitis.

CONCLUSION

Performance status, concurrent chemotherapy, mean esophageal dose and esophageal D2cc are associated with acute esophagitis during definitive treatment of NSCLC. Models that quantitatively account for these factors can be useful in individualizing radiation plans. Mean esophageal dose of 29 Gy and esophageal D2cc of 61 Gy corresponded to a 3% risk of acute grade 3+ esophagitis and merit consideration as contemporary treatment planning constraints.

Assessing Patterns of Practice in Early-Stage Lung Cancer Radiation Therapy: Findings from a Large Statewide Consortium Study on Hypofractionation

PURPOSE/OBJECTIVE(S)

There are many different acceptable radiation dose and fractionation regimens for the treatment of early-stage non-small cell lung cancer (NSCLC), including hypofractionation (HypoRT). There are limited data supporting when to use HypoRT. We investigated which factors led physicians to choose HypoRT rather than stereotactic body radiation therapy (SBRT) or conventional fractionation (CRT) for early-stage NSCLC patients in a statewide consortium.

MATERIALS/METHODS

We examined patients with T1-3N0M0 NSCLC treated at multiple institutions in a statewide consortium from January 2012-July 2022. We classified treatments as SBRT if 5 fractions or fewer, HypoRT if 6-20 fractions, and CRT if 1.8-2 Gy per fraction (Gy/Fx) for 25 or greater fractions. We excluded patients between 20 and 25 fractions as most appeared to be CRT that did not finish treatment (5% of total). We then performed a classification tree using age, race, gender, smoking status, T stage, PTV within 2cm of esophagus, PTV within 2cm of heart, and concurrent chemotherapy as covariates with a three-variable output (SBRT, HypoRT, and CRT). We excluded ECOG as it was not significant on initial analysis and was missing for 100 patients. We also reran the classification tree without CRT as an output to better discriminate between SBRT and HypoRT.

RESULTS

A total of 418 patients were included in the analysis. 184 patients had T1, 123 with T2, and 111 with T3 tumors. In total, 228 patients underwent SBRT (median 50 Gy), 51 patients HypoRT (median 60 Gy), and 139 CRT (median 63 Gy). Covariates significant for discriminating between all three treatment regimens included T2, T3 vs T1, PTV within 2cm of the esophagus, and T3 vs T2. 94% of T1 patients were treated with SBRT. Among T2 and T3 patients, those within 2cm of the esophagus were significantly more likely to be treated with CRT or HypoRT (80% vs 15%). Patients with T3 tumor not within 2cm of the esophagus, were more likely to be treated with CRT or HypoRT than the T2 patients (85% vs 36%). Patients treated with CRT were also more likely to receive chemotherapy, particularly for T3 tumors (80% received concurrent chemotherapy). Excluding CRT as an output variable, proximity to the heart became significant in addition to the other previously described covariates. Notably, the branch with the highest likelihood of HypoRT were patients with T2/T3 tumors within 2 cm of both the esophagus and heart (94% HypoRT vs 6% SBRT). Patients with tumors not close to central structures but with T3 rather than T2 tumors were more likely to be treated with HypoRT as well (62% vs 38%).

CONCLUSION

Based on this large prospective real-world data of early-stage NSCLC, larger tumors and those located near central structures are more likely to be treated with HypoRT. The patient's age, performance status, race, and smoking status were not significant in this analysis. Additional analysis on outcomes and toxicity related to treatments is underway.

Stereotactic Body Radiotherapy (SBRT) for Adrenal Metastases: Practice Patterns at Community-Based Radiotherapy Centers

PURPOSE/OBJECTIVE(S)

To analyze SBRT of adrenal metastases at free-standing centers within a large network in the USA, in order to guide institutional recommendations.

MATERIALS/METHODS

We interrogated records of patients treated with SBRT to adrenal metastases from January 2019 to June 2022 from a database of 13,363 patients who were treated with SBRT at 21 community-based centers clustered into five regions within a network. We reported patient characteristics, frequency, survival rate, and biologically effective dose (BED10) prescribed, respiratory motion capture according to region and treatment year. Survival was calculated by Kaplan-Meier estimates.

RESULTS

A total of 271 patients were treated to metastatic adrenal lesions (2.0% of all SBRT patients). Median age was 69.8 years (range 32-96). Frequency of treatment increased by an average of 4.5% per year over the period. Table 1 gives the frequency of primary tumor sites, histological types, and dose fractionations. It also shows the range of BED10 used. 91% received five fractions, and 6% received 3 fractions. Median BED10 was 72 Gy (mean 68.0 Gy SD = 18.7). The most common regimen was 8 Gy x 5 (n = 75, 28%), but ranged from 5 Gy x 5 (n = 20) to 10 Gy x 5 (n = 34). BED10 varied according to geographic region ranging from 61.2 Gy to 73.0 Gy (p = 0.01). Median BED was 72 or above in 2 of 5 regions and less than 72 in 3 regions. Respiratory motion capture simulation was done in 65.1% of cases and frequency varied across the 5 locations as shown in Table1 from 93.3% in region 1 to 41.7% in region 5 (p<.0001). 4D CT simulation was used in 46.2% of cases and use was relatively stable over time: 52.8% in July to December 2020 and 40.9% from January to June 2022 with no trend over time: p = .7635 At median follow-up 6.6 months (range 0.3-48.5), 203 (74.9%) of patients were alive with a median overall survival of 24.3 months. 1-year and 2-year survival was 72.7% and 51.5% respectively. Use of respiratory motion simulation was not significantly associated with survival p = 0.47.

CONCLUSION

Despite variation in BED10 and respiratory motion management, 2-year overall survival was over 50% in patients treated with SBRT for adrenal metastases in a large community network. Further study will address refinement of recommendations regarding dose and other treatment characteristics and expansion of clinical research in this setting.

Lung metastases treated with image-guided stereotactic body radiation therapy

AIMS

To evaluate outcomes after treatment with image-guided stereotactic body radiation therapy (SBRT) using daily online cone beam computed tomography for malignancies metastatic to the lung.

MATERIALS AND METHODS

Forty-seven lung metastases in 32 patients were treated with volumetrically guided SBRT. The median age was 62 years (21-87). Primaries included colorectal (n = 10), sarcoma (n = 4), head and neck (n = 4), melanoma (n = 3), bladder (n = 2), non-small cell lung cancer (n = 2), renal cell (n = 2), thymoma (n = 2), thyroid (n = 1), endometrial (n = 1) and oesophageal (n = 1). The number of lung metastases per patient ranged from one to three (68% single lesions). SBRT was prescribed to the edge of the target volume to a median dose of 60 Gy (48-65 Gy) in a median of four fractions (four to 10). Most lesions were treated using 12 Gy fractions (92%) to 48 or 60 Gy.

RESULTS

The median follow-up was 27.6 months (7.6-57.1 months). The 1, 2 and 3 year actuarial local control rates for all treated lesions were 97, 92 and 85%, respectively. Two patients with colorectal primaries (four lesions in total) had local failure. The median overall survival was 40 months. The 1, 2 and 3 year overall survival from the time of SBRT completion was 83, 76 and 63%, respectively. There were no grade 4 or 5 toxicities. Grade 3 toxicities (one instance of each) included pneumonitis, dyspnoea, cough, rib fracture and pain.

CONCLUSION

SBRT with daily online cone beam computed tomography for lung metastases achieved excellent local tumour control with low toxicity and encouraging 2 and 3 year survival.

A matched-pair analysis of dose-escalated adaptive image-guided radiotherapy (IGRT) versus pelvic irradiation with brachytherapy boost for intermediate- and high-risk prostate cancer

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Background: The purpose of this study was to compare clinical outcomes in a cohort of intermediate- and high-risk prostate cancer patients treated with either dose-escalated adaptive IGRT or pelvic external beam RT with high-dose rate brachytherapy boost (EBRT+HDR).

Methods: 1,520 patients with clinical stage T1-T3 N0 M0 prostate cancer were treated with either CT-based offline adaptive IGRT (n=1,037) or EBRT+HDR, n=438) at William Beaumont Hospital. For IGRT, the CTV included the prostate and proximal seminal vesicles only. Median dose (minimum to cl-PTV) delivered via 3D conformal RT or intensity-modulated RT was 75.6 Gy (range: 73.8-79.2 Gy). For EBRT+HDR, the whole pelvis was treated to 46 Gy + 2 HDR implants with a median of 10.5 Gy (8.75-11.5 Gy) per implant. 208 patients from each group were matched based on criteria of pretreatment PSA ± 4 ng/mL, same Gleason score, T stage ± 2 sublevels, and use of neoadjuvant androgen deprivation therapy (ADT).

Results: Mean follow-up was 5.1 years for IGRT vs 7.0 years for EBRT+HDR. Mean pretreatment PSA was 9 for both groups. Mean Gleason was 7 for both groups. EBRT+HDR patients were younger (67 vs 71 years, p<0.01) with a higher percentage of positive biopsy cores (51% vs 39%, p<0.01). Intermediate risk patients comprised 78% and 76% for IGRT and EBRT+HDR, respectively (p=0.56). 42% in each treatment group received neoadjuvant or concurrent ADT. 5-year biochemical control (BC) based on the Phoenix definition was 91% for IGRT vs 87% for EBRT+HDR (p=0.60). For intermediate-risk, 5-year BC was 94% vs 87% (p=0.71) and was 86% vs 86% (p=0.83) for high-risk patients. No significant differences were noted between the 2 groups for local recurrence, distant metastasis, clinical failure, overall survival, and cause-specific survival.

Conclusions: In this matched-pair analysis of 416 patients, treatment of intermediate and high-risk prostate cancer with either offline adaptive IGRT or EBRT+HDR yielded excellent clinical outcomes without significant differences. The omission of pelvic radiotherapy in the IGRT patients did not appear to be associated with poorer clinical outcomes with modern high-dose RT.

No significant financial relationships to disclose.

Percentage of positive biopsy cores to predict distant metastasis of prostate cancer after definitive radiation therapy

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Background: To assess the prognostic value of percentage of positive biopsy cores (PPC) and perineural invasion (PNI) in predicting clinical outcome following radiotherapy (RT) for prostate cancer.

Methods: One thousand and fifty-six patients with clinical stage T1-T3 N0 M0 prostate cancer, who had ≥ 4 biopsy cores sampled and complete biopsy core data available, were treated with either adaptive image-guided RT (median 75.6 Gy, n=387), low-dose EBRT (median 66.6 Gy, n=393), or EBRT and high-dose rate brachytherapy boost (n=276) at William Beaumont Hospital (1993-2004). Neoadjuvant and/or adjuvant androgen deprivation (AD) were given to 253 patients (24%). Multivariate cox regression analysis included PPC, gleason score, PSA, T stage, PNI, RT dose, androgen deprivation, and age. Biochemical failure (BF) was scored according to the Phoenix definition. Clinical failure (CF) was defined as any locoregional recurrence (LRR) or distant metastasis (DM). Median follow-up was 7.6 years.

Results: Median cores sampled was 7, median PPC was 33%, and 18% had PNI. On univariate Cox regression, both PPC and PNI were predicators of biochemical failure and clinical failure (all P<0.05). On multivariate Cox regression, PPC, either as continuous or categorical variable, remained an independent predicator of BF, CF, DM, cause-specific survival, and overall survival (all P<0.05). PPC of >50% was associated with significantly higher DM (HR 4.01, 95% CI 1.86-8.61), and its independent predicative value remained significant whether AD was given or not (all P<0.05). Combining ≤50% vs ≥50% PPC with NCCN risk group stratification demonstrated added prognostic value of DM for intermediate-risk (HR 5.44, 95% CI 1.78-16.6) and high-risk groups (HR 4.39, 95% CI 1.70-2.84), with or without AD (all P<0.05). On multivariate Cox regression, PNI was an independent predicator of LRR only (HR 2.51, 95% CI 1.18-5.33).

Conclusions: PPC is an independent and powerful predicator of DM for intermediate- and high-risk prostate cancer, regardless the use of AD. It should be considered for risk stratification and when designing for future trials testing adjuvant treatment after definitive RT for prostate cancer.

No significant financial relationships to disclose.

Abstract P4-10-04: Rates of Second Malignancies after Definitive Local Treatment for Ductal Carcinoma In Situ of the Breast

Background: We analyzed the risk of developing second malignancies in patients with ductal carcinoma in situ (DCIS) undergoing surgery and radiotherapy (S+RT) versus surgery alone (S).

Material and Methods: The S+RT cohort consisted of 256 women treated with breast conserving therapy at William Beaumont Hospital. The S cohort consisted of 2,788 women with DCIS in the regional SEER database treated during the same time period. A matched-pair analysis was performed in which each S+RT patient was randomly matched with 8 S patients (total of 2048 patients). Matching criteria included age +/− 2 years. The rates of second malignancies were analyzed overall and as contralateral breast versus non-breast cancers and by organ system. Results: Median follow-up was 13.7 years for the S+RT cohort and 13.3 years for the S cohort. The overall 10-/15-year rate of second malignancies among the S+RT and S cohorts were 14.2%/24.2% and 16.4%/22.6%, respectively (p=0.668). The 15-year second contralateral breast cancer rate was 14.2% in the S+RT cohort and 10.3% in the S cohort (p=0.439). The 15- year risk of a second non-breast malignancy was 14.2% for the S+RT cohort and 13.4% for the S alone cohort (p=0.660). When analyzed by organ system, the 10- and 15-year rates of second malignancies did not differ between the S+RT and the S cohorts for pulmonary, gastrointestinal, central nervous system, gynecological, genitourinary, lymphoid, sarcomatoid, head and neck, or unknown primary tumors.

Discussion: Compared with S alone, S +RT was not associated with an overall increased risk of second malignancies in women with DCIS.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-10-04.

Outcomes after stereotactic lung radiotherapy or wedge resection for stage I non-small cell lung cancer (NSCLC)

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Background: To compare clinical outcomes between lung stereotactic radiotherapy (SBRT) and wedge resection for stage I NSCLC. Methods: 112 cases of T1–2N0 NSCLC were treated with wedge resection (n=69) or image-guided lung SBRT (n=43) from 2/2003–8/2008. SBRT patients were treated on a phase II trial. All patients were ineligible for anatomic lobectomy; 93% undergoing SBRT were medically inoperable; 7% refused surgery. Mean FEV1 and DLCO were 1.58L and 13.9ml/min/mmHg for wedge cases vs 1.29L and 10.1ml for SBRT (p<0.01, p<0.01). Mean Charlson Co-morbidity Index and median age were 3 and 74y for wedge vs 4 and 77y for SBRT (p<0.01, p=0.04). Patients were staged using CT, 18FDG PET-CT, pulmonary function testing, and chemistries. SBRT patients had bone scan and brain MRI. Mediastinoscopies were performed for 28% of wedge cases vs.16% for SBRT (p=NS). SBRT was prescribed as 48 (T1) or 60 (T2) Gy in 4–5 fractions to the edge of the target volume. Adjuvant chemotherapy was given to 22% of SBRT vs12% of wedge patients (p=NS). Results: Median potential follow-up=2.3y. No significant differences were identified in local (LR), regional (RR), or locoregional recurrence (LRR), distant metastasis (DM), freedom from any failure (FFF), overall survival, or cause-specific survival between the two groups (Table); however, trends toward reduced LR and improved FFF were found with SBRT. Results excluding cases of synchronous primary tumors or pathologicalT4 (satellite lesion at wedge) are also shown, with FFF significantly better for SBRT. Multivariate analysis showed tumor grade to predict LR; LR to predict DM; LR and angiolymphatic invasion to predict RR and RR, (+)margin, FEV1, and pathologic diameter OS (p=0.06, p=0.08, p=0.01, p=0.04) in wedge cases. Conclusions: Both lung SBRT and wedge resection are reasonable treatment options for Stage I NSCLC patients ineligible for anatomic lobectomy. SBRT showed trends toward reduced LR and failure. Additional follow-up will be needed to verify durability of these findings.

[Table: see text]

No significant financial relationships to disclose.

Defining a dose-response relationship with radiotherapy for prostate cancer: is more really better?

PURPOSE

Data were reviewed addressing the association between radiation therapy (RT) dose and treatment outcome for localized prostate cancer to help clarify the existence of a potential dose-response relationship.

METHODS AND MATERIALS

Articles were identified through the MEDLINE database, CancerLit database, and reference lists of relevant articles. Studies were categorized into four groups based upon the endpoint analyzed, including biochemical control (BC), local control (LC), pathologic control (PC), and cause-specific survival (CSS). The impact of increasing RT dose with each endpoint was recorded.

RESULTS

Twenty-two trials involving a total of 11,297 patients were identified. Of the 11 trials addressing the association of RT dose with LC, 9 showed statistically significant improvements. Of the 12 trials that reported BC with RT dose, all showed statistically significant improvements. Two out of 4 studies analyzing PC with increasing dose showed a positive correlation. Finally, 3 out of 9 studies addressing RT dose with CSS showed statistically significant improvements. Despite inconclusive results, patients with poor risk features (e.g., prostate-specific antigen [PSA] > or = 10, Gleason score [GS] > or = 7, or tumor stage > or = T2b) were most likely to benefit from increasing dose with respect to each endpoint. However, the optimal RT dose and the magnitude of benefit of dose escalation could not be identified.

CONCLUSIONS

Although RT dose appears to correlate with various measures of treatment outcome, objective, high-quality data addressing this critical issue are still lacking. At the present time, the absolute improvement in outcome due to dose escalation, the subset of patients benefitting most, and the optimal dose remain to be defined.

Clinicopathologic implications of E-cadherin reactivity in patients with lobular carcinoma in situ of the breast

BACKGROUND

The current study addressed two questions pertaining to lobular carcinoma in situ (LCIS) of the breast. First, does the risk of a subsequent carcinoma decrease over time after an LCIS biopsy and second, what is the clinical significance of E-cadherin-reactive LCIS?

METHODS

Eighty-two consecutive patients with a biopsy containing LCIS only, no prior history of breast carcinoma, and follow-up information available for the period 1955-1976 were reviewed. No patients underwent a mastectomy for LCIS. Four hundred eighty-six sections were stained with E-cadherin. E-cadherin reactivity was correlated with clinicopathologic features of the LCIS and subsequent tumors. The mean number of blocks stained per case was 5.9. The mean follow-up period was 21.6 years.

RESULTS

Sixteen patients (19.5%) developed 21 subsequent invasive carcinomas (9 ipsilateral, 2 contralateral, and 5 bilateral carcinomas). The 10-year and 20-year actuarial rates of developing subsequent carcinoma were 7.8% and 15.4%, respectively. Six of the 21 carcinomas (29%) developed after 20 years. Nine LCIS cases (10.9%) had focal E-cadherin reactivity. When compared with patients with nonreactive LCIS, patients with E-cadherin-reactive LCIS more frequently developed a subsequent ipsilateral carcinoma that had a ductal component (55.5% vs. 12.3%; P < 0.01). The subsequent carcinomas also developed after significantly shorter time periods (mean of 7.6 years vs. 19.6 years; P < 0.01).

CONCLUSIONS

LCIS appears to confer a persistent, increased risk of subsequent breast carcinoma that does not appear to decrease over time. E-cadherin reactivity appears to identify a subset of LCIS patients with risk factors for subsequent carcinoma similar to those of patients with low-grade intraductal carcinoma.

The use of high-dose-rate brachytherapy alone after lumpectomy in patients with early-stage breast cancer treated with breast-conserving therapy

PURPOSE

We present the preliminary results of our in-house protocol using outpatient high-dose-rate (HDR) brachytherapy as the sole radiation modality following lumpectomy in patients with early-stage breast cancer.

METHODS AND MATERIALS

Thirty-seven patients with 38 Stage I-II breast cancers received radiation to the lumpectomy cavity alone using an HDR interstitial implant with (192)Ir. A minimum dose of 32 Gy was delivered on an outpatient basis in 8 fractions of 4 Gy to the lumpectomy cavity plus a 1- to 2-cm margin over consecutive 4 days.

RESULTS

Median follow-up is 31 months. There has been one ipsilateral breast recurrence for a crude failure rate of 2.6% and no regional or distant failures. Wound healing was not impaired in patients undergoing an open-cavity implant. Three minor breast infections occurred, and all resolved with oral antibiotics. The cosmetic outcome was good to excellent in all patients.

CONCLUSION

In selected patients with early-stage breast cancer, treatment of the lumpectomy cavity alone with outpatient HDR brachytherapy is both technically feasible and well tolerated. Early results are encouraging, however, longer follow-up is necessary before equivalence to standard whole-breast irradiation can be established and to determine the most optimal radiation therapy technique to be employed.

Relationship between excision volume, margin status, and tumor size with the development of local recurrence in patients with ductal carcinoma-in-situ treated with breast-conserving therapy

BACKGROUND AND OBJECTIVES

We reviewed our institution's experience treating patients with ductal carcinoma-in-situ (DCIS) with breast-conserving therapy (BCT) to help define the interrelationship between excision volume, margin status, and tumor size with local recurrence.

METHODS

From January 1980 to December 1993, 146 patients received BCT for DCIS. All patients underwent excisional biopsy and 95 cases (64%) underwent re-excision. Each patient received whole breast radiation to a median dose of 45 Gy. An additional 139 cases (94%) received a supplemental boost to the tumor bed (median total dose 60.4 Gy). The median follow-up is 7.2 years.

RESULTS

Seventeen patients developed an ipsilateral breast failure for a 5- and 10-year actuarial rate of 10.2 and 12.4%, respectively. On multivariate analysis, patient age, margin status, the number of slides containing DCIS, the number of DCIS/cancerization of lobules (COL) foci near (< 5 mm) the margin, and a smaller volume of excision (< 60 cm(3)) were all independently associated with outcome. Although the local recurrence rate generally decreased as margin distance increased, these differences did not achieve statistical significance unless the volume of excision was taken into consideration.

CONCLUSIONS

These findings suggest that the success of BCT is directly related to the degree of surgical removal of DCIS and that margin status alone may be suboptimal in defining excision adequacy.

Accelerated treatment of breast cancer

PURPOSE

Radiation therapy (RT) restricted to the tumor bed, by means of an interstitial implant, and lasting 4 to 5 days after lumpectomy was prospectively evaluated in early-stage breast cancer patients treated with breast-conserving therapy (BCT). The goals of the study were to determine whether treatment time can be reduced and whether elective treatment of the entire breast is necessary.

MATERIALS AND METHODS

Between January 1993 and January 2000, 174 cases of early-stage breast cancer were managed with lumpectomy followed by RT restricted to the tumor bed using an interstitial implant. Each brachytherapy patient was matched with one external-beam RT (ERT) patient derived from a reference group of 1,388 patients treated with standard BCT. Patients were matched for age, tumor size, histology, margins of excision, absence of an extensive intraductal component, nodal status, estrogen receptor status, and tamoxifen use. Median follow-up for both the ERT and brachytherapy groups was 36 months.

RESULTS

No statistically significant differences were noted in the 5-year actuarial rates of ipsilateral breast treatment failure or locoregional failure between ERT and brachytherapy patients (1% v 0%, P =.31 and 2% v 1%, P =.63, respectively). In addition, there were no statistically significant differences noted in rates of distant metastasis (6% v 3%, P =.24), disease-free survival (87% v 91%, P =.55), overall survival (90% v 93%, P =.66), or cause-specific survival (97% v 99%, P =.28).

CONCLUSION

Accelerated treatment of breast cancer using an interstitial implant to deliver radiation to the tumor bed alone over 4 to 5 days seems to produce 5-year results equivalent to those achieved with conventional ERT. Extended follow-up will be required to determine the long-term efficacy of this treatment approach.

Impact of boost technique on outcome in early-stage breast cancer patients treated with breast-conserving therapy

We reviewed our institution's experience treating early-stage breast cancer patients with breast-conserving therapy (BCT) to determine the impact of boost technique on outcome. A total of 552 patients with stage I and II breast cancer were managed with BCT. All patients were treated with a partial mastectomy and radiation therapy (RT). RT consisted of 45 Gy to 50 Gy external beam irradiation to the whole breast followed by a boost to the tumor bed using either electrons (232 patients), photons (15 patients), or an interstitial implant (316 patients). Local control and cosmetic outcome was compared among three patient groups based on the type of boost used. Forty-one patients had a recurrence of cancer in the treated breast for 5-, 10-, and 13-year actuarial local recurrence rates of 2.8%, 7.5%, and 11.2%, respectively. There were no significant differences in the local recurrence rates or cosmetic outcome using electrons, photons, or an interstitial implant. On multivariate analysis, only young age and margin status were associated with local recurrence. Stage I and II breast cancer patients undergoing BCT can be effectively managed with electron, photon, or interstitial implant boost techniques. Long-term local control and cosmetic outcome are excellent regardless of which boost technique is used.

Intensity modulation to improve dose uniformity with tangential breast radiotherapy: initial clinical experience

PURPOSE

We present a new technique to improve dose uniformity and potentially reduce acute toxicity with tangential whole-breast radiotherapy (RT) using intensity-modulated radiation therapy (IMRT). The technique of multiple static multileaf collimator (sMLC) segments was used to facilitate IMRT.

METHODS AND MATERIALS

Ten patients with early-stage breast cancer underwent treatment planning for whole-breast RT using a new method of IMRT. The three-dimensional (3D) dose distribution was first calculated for equally weighted, open tangential fields (i.e., no blocks, no wedges). Dose calculation was corrected for density effects with the pencil-beam superposition algorithm. Separate MLC segments were constructed to conform to the beam's-eye-view projections of the 3D isodose surfaces in 5% increments, ranging from the 120% to 100% isodose surface. Medial and lateral MLC segments that conformed to the lung tissue in the fields were added to reduce transmission. Using the beam-weight optimization utility of the 3D treatment planning system, the sMLC segment weights were then determined to deliver the most uniform dose to 100 reference points that were uniformly distributed throughout the breast. The accuracy of the dose calculation and resultant IMRT delivery was verified with film dosimetry performed on an anthropomorphic phantom. For each patient, the dosimetric uniformity within the breast tissue was evaluated for IMRT and two other treatment techniques. The first technique modeled conventional practice where wedges were derived manually without consideration of inhomogeneity effects (or density correction). A recalculation was performed with density correction to represent the actual dose delivered. In the second technique, the wedges were optimized using the same beam-weight optimization utility as the IMRT plan and included density correction. All dose calculations were based on the pencil-beam superposition algorithm.

RESULTS

For the sMLC technique, treatment planning required approximately 60 min. Treatment delivery (including patient setup) required approximately 8-10 min. Film dosimetry measurements performed on an anthropomorphic phantom generally agreed with calculations to within +/- 3%. Compared to the wedge techniques, IMRT with sMLC segments resulted in smaller "hot spots" and a lower maximum dose, while maintaining similar coverage of the treatment volume. A median of only 0.1% of the treatment volume received > or = 110% of the prescribed dose when using IMRT versus 10% with standard wedges. A total of 6-8 segments were required with the majority of the dose delivered via the open segments. The addition of the lung-block segments to IMRT was of significant benefit for patients with a greater proportion of lung parenchyma within the irradiated volume. Since August 1999, 32 patients have been treated in the clinic with the IMRT technique. No patient experienced RTOG grade III or greater acute skin toxicity.

CONCLUSION

The use of intensity modulation with an sMLC technique for tangential breast RT is an efficient and effective method for achieving uniform dose throughout the breast. It is dosimetrically superior to the treatment techniques that employ only wedges. Preliminary findings reveal minimal or no acute skin reactions for patients with various breast sizes.

Matched-pair analysis of conformal high-dose-rate brachytherapy boost versus external-beam radiation therapy alone for locally advanced prostate cancer

PURPOSE

We performed a matched-pair analysis to compare our institution's experience in treating locally advanced prostate cancer with external-beam radiation therapy (EBRT) alone to EBRT in combination with conformal interstitial high-dose-rate (HDR) brachytherapy boosts (EBRT + HDR).

MATERIALS AND METHODS

From 1991 to 1998, 161 patients with locally advanced prostate cancer were prospectively treated with EBRT + HDR at William Beaumont Hospital, Royal Oak, Michigan. Patients with any of the following characteristics were eligible for study entry: pretreatment prostate-specific antigen (PSA) level of >/= 10.0 ng/mL, Gleason score >/= 7, or clinical stage T2b to T3c. Pelvic EBRT (46.0 Gy) was supplemented with three (1991 through 1995) or two (1995 through 1998) ultrasound-guided transperineal interstitial iridium-192 HDR implants. The brachytherapy dose was escalated from 5.50 to 10.50 Gy per implant. Each of the 161 EBRT + HDR patients was randomly matched with a unique EBRT-alone patient. Patients were matched according to PSA level, Gleason score, T stage, and follow-up duration. The median PSA follow-up was 2.5 years for both EBRT + HDR and EBRT alone.

RESULTS

EBRT + HDR patients demonstrated significantly lower PSA nadir levels (median, 0.4 ng/mL) compared with those receiving EBRT alone (median, 1.1 ng/mL). The 5-year biochemical control rates for EBRT + HDR versus EBRT-alone patients were 67% versus 44%, respectively (P <.001). On multivariate analyses, pretreatment PSA, Gleason score, T stage, and the use of EBRT alone were significantly associated with biochemical failure. Those patients in both treatment groups who experienced biochemical failure had a lower 5-year cause-specific survival rate than patients who were biochemically controlled (84% v 100%; P <.001).

CONCLUSION

Locally advanced prostate cancer patients treated with EBRT + HDR demonstrate improved biochemical control compared with those who are treated with conventional doses of EBRT alone.

Differences in the pathologic features of ductal carcinoma in situ of the breast based on patient age

BACKGROUND

Young patient age at diagnosis has been reported as a risk factor for recurrence in patients with ductal carcinoma in situ (DCIS) of the breast treated with breast-conserving therapy (BCT). The authors examined pathologic features of DCIS in three different age groups of patients to identify differences that might explain why young patient age at the time of diagnosis is a risk factor for recurrence.

METHODS

Excised specimens from 177 breasts of 172 patients with DCIS treated with BCT were studied. All slides from all specimens were reviewed. Patients were divided into 3 age groups: those age < 45 years, those ages 45-59 years, and those age >/= 60 years. The histologic features that were quantified included most common and highest nuclear grades, DCIS architectural pattern, amount of central necrosis (quartiles), calcifications, amount of DCIS, and number of terminal duct lobular units (TDLUs) with cancerization of lobules (COL) within 0.42 cm of the margin, margin status, and size and volume of excision specimens.

RESULTS

Patients age < 45 years at the time of diagnosis more frequently had higher nuclear grade DCIS (highest nuclear Grade 3: 69%, 60%, and 39%; P = 0.003), respectively and central necrosis (72%, 62%, and 44%; P = 0. 01), respectively. Although not statistically significant, younger patients tended to have comedo subtype DCIS more often (31%, 23%, and 19%; P = 0.35), respectively. Younger patients also more often had smaller initial biopsy specimen maximum dimensions (4.3 cm, 5.2 cm, and 5.7 cm; P = 0.004), respectively, with close or positive margins (89%, 61%, and 64%; P = 0.03), and more TDLUs with COL in the 0.42-cm rim of tissue adjacent to the margin (5.2, 3.6, and 1.9; P = 0.23), respectively. No other features including the amount of DCIS when classified as > 50% or > 75% of ducts, calcifications within DCIS ducts, pattern of DCIS involvement, number of slides examined, number of slides with DCIS, and mean number of DCIS ducts near the margin were found to occur more frequently in younger patients.

CONCLUSIONS

Younger patients with DCIS may have an increased risk of local recurrence when treated with BCT due to smaller initial excision volumes, a greater proportion of high nuclear grade DCIS, and central necrosis.

Use of conformal high-dose rate brachytherapy for management of patients with prostate cancer: optimizing dose escalation

PURPOSE

We reviewed our institution's experience treating patients with locally advanced prostate cancer using high-dose rate (HDR) conformal brachytherapy. Treatment technique, interim results, and toxicity are reviewed.

MATERIALS AND METHODS

From November 1991 to May 1998, 161 patients with locally advanced prostate cancer were treated on a dose escalation trial of external-beam radiation therapy (EBRT) combined with HDR conformal brachytherapy boosts. Patients with any of the following characteristics were acceptable for enrollment: pretreatment prostate-specific antigen (PSA) > or =10 ng/mL, Gleason score > or =7, or clinical stage T2b or higher. All patients received pelvic EBRT to a median dose of 46 Gy. Transperineal ultrasound-guided temporary HDR brachytherapy implant boosts were performed in the first, second, and third week of EBRT. Seventy-two patients were boosted with three implants (boost dose 5.50 to 6.50 Gy), and 89 patients received two implants (boost dose 8.25 to 10.50 Gy). All implants were placed using interactive real-time dosimetry. Biochemical failure was calculated using the American Society for Therapeutic Radiology and Oncology Consensus Panel definition. Median follow-up was 2.8 years (range 0.3-7.2).

RESULTS

The 2- and 5-year actuarial biochemical control rates were 86% and 67%, respectively. The 5-year actuarial biochemical control rates for patients with a pretreatment PSA < or =3.9, 4.0-9.9, 10.0-19.9, and > or =20.0 ng/mL were 80%, 87%, 56%, and 54%, respectively. Factors associated with biochemical failure on multivariate analysis included the pretreatment PSA, Gleason score, PSA nadir, and time to PSA nadir. A total of 6 patients (4%) developed grade 3 late toxicity consisting of urethral stricture (5 patients) or incontinence (1 patient). Forty- four patients (27%) developed impotence after radiation therapy.

CONCLUSIONS

Conformal HDR brachytherapy boosts appear to offer a safe, reproducible, and effective method of dose escalation in patients with locally advanced prostate cancer treated with RT. Interim results with this technology reveal biochemical control rates paralleling those achieved with three-dimensional conformal EBRT and other forms of treatment.

The correlation of serial prostate specific antigen measurements with clinical outcome after external beam radiation therapy of patients for prostate carcinoma

BACKGROUND

The authors analyzed retrospectively their institution's experience in treating patients with localized prostate carcinoma with external beam radiation therapy (EBRT) to determine the correlation of various biochemical failure (BF) definitions with clinical failure and cause specific survival (CSS).

METHODS

Between January 1987 and December 1997, 1,094 patients with clinical T1-T3N0M0 prostate carcinoma were treated with definitive EBRT alone at William Beaumont Hospital, Royal Oak, Michigan. All patients received EBRT alone (no adjuvant hormones) to a median total prostate dose of 66.6 grays (Gy) (range, 59.4-70.4 Gy). Multiple BF definitions were tested for their correlation with clinical failure and cause specific death (CSD = 1-CSS). All BF definitions were tested for sensitivity, specificity, and accuracy of predicting subsequent clinical failure and CSD. Positive and negative predictive values were calculated in the form of 10-year actuarial clinical failure and CSD rates. Analyses were performed on all 1,094 patients as well as for those 727 patients who had at least 5 post-RT prostate specific antigen (PSA) level measurements and who did not receive hormonal therapy for post-RT PSA elevations. The median PSA follow-up was 4.0 years for the entire population and 4.5 years for those 727 patients included in the second analysis.

RESULTS

In the entire population, 167 patients (15%) experienced clinical failure corresponding to 5- and 10-year actuarial rates of 16% and 34%, respectively. The correlation of various BF definitions with outcome was calculated in those 727 patients who did not receive hormonal therapy. For these patients, BF (as defined by the American Society for Therapeutic Radiology and Oncology Consensus Panel) yielded a 73% sensitivity, 76% specificity, and 75% overall accuracy for predicting clinical failure and a 74% sensitivity, 69% specificity, and 69% overall accuracy for predicting CSD. The 10-year clinical failure rate for those 251 patients demonstrating 3 consecutive PSA rises (BF) was 64% versus 14% for those patients who did not meet these criteria (biochemically controlled [BC]). As expected, definitions requiring only two rises were more sensitive but less specific in predicting clinical failure than those definitions requiring three or four rises. Because there were dramatically more clinically controlled patients (85%) than clinical failures (15%), the overall accuracy for each definition more closely approximated its specificity. The definitions classifying BF as a postnadir increase of > or = 3 or > or = 4 ng/mL above the nadir yielded the highest accuracies of 87% and 88%, respectively. In addition, these definitions also appeared to provide the greatest separation in clinical failure rates between BC and BF patients, an absolute difference of 77% and 76%, respectively.

CONCLUSIONS

The correlation between BF and clinical failure and CSD varies markedly depending on the BF definition used. Definitions incorporating a fixed baseline (the nadir level) and the postnadir PSA profile may have better correlation with clinical failure than definitions using the nadir only or a specific number of consecutive rises in which a variable baseline "resets" after a PSA decrease.

Interim report of image-guided conformal high-dose-rate brachytherapy for patients with unfavorable prostate cancer: the William Beaumont phase II dose-escalating trial

PURPOSE

We analyzed our institution's experience treating patients with unfavorable prostate cancer in a prospective Phase II dose-escalating trial of external beam radiation therapy (EBRT) integrated with conformal high-dose-rate (HDR) brachytherapy boosts. This interim report discusses treatment outcome and prognostic factors using this treatment approach.

METHODS AND MATERIALS

From November 1991 through February 1998, 142 patients with unfavorable prostate cancer were prospectively treated in a dose-escalating trial with pelvic EBRT in combination with outpatient HDR brachytherapy at William Beaumont Hospital. Patients with any of the following characteristics were eligible: pretreatment prostate-specific antigen (PSA) >/= 10.0 ng/ml, Gleason score >/= 7, or clinical stage T2b or higher. All patients received pelvic EBRT to a median total dose of 46.0 Gy. Pelvic EBRT was integrated with ultrasound-guided transperineal conformal interstitial iridium-192 HDR implants. From 1991 to 1995, 58 patients underwent three conformal interstitial HDR implants during the first, second, and third weeks of pelvic EBRT. After October 1995, 84 patients received two interstitial implants during the first and third weeks of pelvic EBRT. The dose delivered via interstitial brachytherapy was escalated from 5.50 Gy to 6.50 Gy for each implant in those patients receiving three implants, and subsequently, from 8.25 Gy to 9.50 Gy per fraction in those patients receiving two implants. To improve implant quality and reduce operator dependency, an on-line, image-guided interactive dose optimization program was utilized during each HDR implant. No patient received hormonal therapy unless treatment failure was documented. The median follow-up was 2.1 years (range: 0.2-7.2 years). Biochemical failure was defined according to the American Society for Therapeutic Radiology and Oncology Consensus Panel definition.

RESULTS

The pretreatment PSA level was >/= 10.0 ng/ml in 51% of patients. The biopsy Gleason score was >/= 7 in 58% of cases, and 75% of cases were clinical stage T2b or higher. Despite the high frequency of these poor prognostic factors, the actuarial biochemical control rate was 89% at 2 years and 63% at 5 years. On multivariate analysis, a higher pretreatment PSA level, higher Gleason score, higher PSA nadir level, and shorter time to nadir were associated with biochemical failure. In the entire population, 14 patients (10%) experienced clinical failure at a median interval of 1.7 years (range: 0.2-4.5 years) after completing RT. The 5-year actuarial clinical failure rate was 22%. The 5-year actuarial rates of local failure and distant metastasis were 16% and 14%, respectively. For all patients, the 5-year disease-free survival, overall survival, and cause-specific survival rates were 89%, 95%, and 96%, respectively. The 5-year actuarial rate of RTOG Grade 3 late complications was 9% with no patient experiencing Grade 4 or 5 acute or late toxicity.

CONCLUSION

Pelvic EBRT in combination with image-guided conformal HDR brachytherapy boosts appears to be an effective treatment for patients with unfavorable prostate cancer with minimal associated morbidity. Our dose-escalating trial will continue.

Mammographically detected ductal carcinoma in situ treated with conservative surgery with or without radiation therapy: patterns of failure and 10-year results

OBJECTIVE

The authors reviewed their institution's experience treating mammographically detected ductal carcinoma in situ (DCIS) of the breast with breast-conserving therapy (BCT) to determine 10-year rates of local control and survival, patterns of failure, and factors associated with outcome.

SUMMARY BACKGROUND DATA

From January 1980 to December 1993, 177 breasts in 172 patients were treated with BCT for mammographically detected DCIS of the breast at William Beaumont Hospital, Royal Oak, Michigan.

METHODS

All patients underwent an excisional biopsy, and 65% were reexcised. Thirty-one breasts (18%) were treated with excision alone, whereas 146 breasts (82%) received postoperative radiation therapy (RT). All patients undergoing RT received whole-breast irradiation to a median dose of 50.0 Gy. One hundred thirty-six (93%) received a boost to the tumor bed for a median total dose of 60.4 Gy. Median follow-up was 5.9 years for the lumpectomy alone group and 7.2 years for the lumpectomy + RT group.

RESULTS

In the entire population, 15 patients had an ipsilateral breast recurrence. The 5- and 10-year actuarial rates of ipsilateral breast recurrence were 7.8% and 7.8% for lumpectomy alone and 8.0% and 9.2% for lumpectomy + RT, respectively. Eleven of the 15 recurrences developed within or immediately adjacent to the lumpectomy cavity and were designated as true recurrences or marginal misses (TMM). Four recurred elsewhere in the breast. Eleven of the 15 recurrences were invasive, whereas 4 were pure DCIS. Only one patient died of disease, yielding 5- and 10-year actuarial cause-specific survival rates of 100% and 99.2%, respectively. Eleven patients were diagnosed with subsequent contralateral breast cancer, yielding 5- and 10-year actuarial rates of 5.1% and 8.3%, respectively. Clinical, pathologic, and treatment-related factors were analyzed for an association with ipsilateral breast failure or TR/MM. No factors were significantly associated with ipsilateral breast failure. In the entire population, the omission of RT and younger age at diagnosis were significantly associated with TR/MM. Patients younger than 45 years at diagnosis had a significantly higher rate of TR/MM in both the lumpectomy + RT and lumpectomy alone groups. None of the 37 patients who received a postexcisional mammogram had an ipsilateral breast failure versus 15 in the patients who did not receive a postexcisional mammogram.

CONCLUSIONS

Patients diagnosed with mammographically detected DCIS of the breast appear to have excellent 100-year rates of local control and overall survival when treated with BCT. These results suggest that the use of RT reduces the risk of local recurrence and that patients diagnosed at a younger age have a higher rate of local recurrence with or without the use of postoperative RT.

Factors associated with local recurrence of mammographically detected ductal carcinoma in situ in patients given breast-conserving therapy

BACKGROUND

The authors reviewed their institution's experience treating patients with mammographically detected ductal carcinoma in situ (DCIS) of the breast with breast-conserving therapy (BCT) to determine 10-year rates of local control and survival and to identify factors associated with local recurrence.

METHODS

From January 1980 to December 1993, 132 breasts in 130 patients were treated with BCT for mammographically detected DCIS at William Beaumont Hospital, Royal Oak, Michigan. All patients underwent an excisional biopsy, and 64% were reexcised. All patients received postoperative whole-breast irradiation to a median dose of 45.0 Gray (Gy) (range: 43.1-56.0 Gy). One hundred twenty-four cases (94%) received a boost to the tumor bed for a median total dose of 60.4 Gy (range: 45.0-71.8 Gy). All cases underwent complete pathologic review by one pathologist. The median follow-up was 7.0 years.

RESULTS

Of the entire study group, 13 patients developed recurrence within the ipsilateral breast, for 5- and 10-year actuarial rates of 8.9% and 10.3%, respectively. Nine of the 13 recurrences (69%) occurred within or immediately adjacent to the lumpectomy cavity and were designated as true recurrences or marginal misses (TR/MM). Four patients (31%) had recurrence elsewhere in the breast. Ten of the 13 recurrences (77%) were invasive, whereas 3 (23%) were pure DCIS. Only 1 patient died of disease, corresponding to 5- and 10-year actuarial cause specific survival rates of 100% and 99.0%, respectively. Multiple clinical, pathologic, and treatment-related factors were analyzed for association with ipsilateral breast failure or TR/MM. In multivariate analysis, only the absence of pathologic calcifications was significantly associated with ipsilateral breast failure. When specifically analyzed for TR/MM, younger age at diagnosis, number of slides with DCIS, number of DCIS and cancerization of lobules (COL) foci within 5 mm of the margin, and the absence of pathologic calcifications demonstrated a statistically significant association. Close or positive margin status did not significantly predict for either TR/MM (P = 0.14) or ipsilateral breast failure (P = 0.19).

CONCLUSIONS

In patients with mammographically detected DCIS treated with BCT, adequate excision of all DCIS prior to RT can result in improved rates of local control. However, margin status may not adequately predict complete tumor extirpation. The volume of DCIS within 5 mm of the margin appears to be a more reliable surrogate for the adequacy of excision. In addition, young patient age and the absence of pathologic calcifications are independent risk factors for the development of local recurrence.

A comparison of external beam radiation therapy versus radical prostatectomy for patients with low risk prostate carcinoma diagnosed, staged, and treated at a single institution

BACKGROUND

The authors retrospectively reviewed their institution's long term experience treating a group of comparably staged low risk prostate carcinoma patients with either radical prostatectomy or external beam radiation therapy (RT) to determine whether the method of treatment resulted in significant differences in biochemical control and/or survival.

METHODS

From January of 1987 through December of 1994, 382 patients (157 who underwent radical prostatectomy and 225 who received external beam RT) were treated with curative intent for localized prostate carcinoma at William Beaumont Hospital. All patients had a pretreatment serum prostate specific antigen (PSA) level < or =10.0 ng/mL and a biopsy Gleason score </=6. Patients treated with RT received a median dose of 66.6 gray (Gy) (range, 59.2-70.2 Gy) to the prostate. Patients treated surgically underwent radical retropubic prostatectomy with a pelvic lymph node dissection. For surgical patients, biochemical failure was defined as a detectable PSA level > or =0.2 ng/mL at any time after prostatectomy. For RT patients, biochemical failure was defined according to the American Society for Therapeutic Radiology and Oncology Consensus Panel definition. Pretreatment PSA levels and Gleason scores were not significantly different between patients treated with radical prostatectomy or RT. The median follow-up in each treatment group was 5.5 years.

RESULTS

The 7-year actuarial rates of biochemical control and cause specific survival were not significantly different between patients treated either with radical prostatectomy or RT (67% vs. 69% for biochemical control and 99% vs. 97% for cause specific survival, respectively). A number of clinical, pathologic, and treatment-related factors were analyzed for an association with biochemical failure (i.e., age, pretreatment PSA, Gleason score, and treatment modality). Only pretreatment PSA and Gleason score were significantly related to outcome in both univariate and multivariate analyses.

CONCLUSIONS

Low risk prostate carcinoma patients with similar pretreatment PSA levels and biopsy Gleason scores treated at the same institution with either radical prostatectomy or RT achieved similar 7-year rates of biochemical control and cause specific survival, regardless of treatment technique. These findings suggest that for patients with pretreatment PSA levels </=10 ng/mL and Gleason scores </=6, conventional doses of external beam RT and radical retropubic prostatectomy can be expected to produce comparable treatment results unaffected by age at diagnosis.

Improving the dosimetric coverage of interstitial high-dose-rate breast implants

PURPOSE/OBJECTIVE

We performed a retrospective computed tomography (CT)-based three-dimensional (3D) dose-volume analysis of high-dose-rate (HDR) interstitial breast implants to evaluate the adequacy of lumpectomy cavity coverage, and then designed a simple, reproducible algorithm for dwell-time adjustment to correct for underdosage of the lumpectomy cavity.

METHODS AND MATERIALS

Since March 1993, brachytherapy has been used as the sole radiation modality after lumpectomy in selected protocol patients with early-stage breast cancer treated with breast-conserving therapy. In this protocol, all patients received 32 Gy in 8 fractions of 4 Gy over 4 days. Eleven patients treated with HDR brachytherapy who underwent CT scanning after implant placement were included in this analysis. For each patient, the postimplant CT dataset was transferred to a 3D treatment planning system, and the relevant tissue volumes were outlined on each axial slice. The implant dataset, including the dwell positions and dwell times, were imported into the 3D planning system and then registered to the visible implant template in the CT dataset. The calculated dose distribution was analyzed with respect to defined volumes via dose-volume histograms. Due to the variability of lumpectomy cavity coverage discovered in this 3D quality assurance analysis, dwell times at selected positions were adjusted in an attempt to improve dosimetric coverage of the lumpectomy cavity. Using implant data from 5 cases, a dwell-time adjustment algorithm was designed and was then tested on 11 cases. In this algorithm, a point P was identified using axial CT images, which was representative of the underdosed region within the cavity. The distance (d) from point P to the nearest dwell position was measured. A number of dwell positions (N) nearest to point P were selected for dwell time adjustment. The algorithm was tested by increasing the dwell times of a variable number of positions (N = 1, 3, 5, 7, 10, and 20) by a weighting factor (alpha), where alpha = f(d) and alpha > 1, and subsequently performing 3D dose-volume analysis to evaluate the improvement in lumpectomy cavity coverage.

RESULTS

Before adjustment in the 11 implants, the median proportion of the lumpectomy cavity and target volume that received at least the prescription dose was 85% and 68%, respectively. After dwell-time adjustment, lumpectomy cavity coverage was significantly improved in all 11 cases. The median distance from point P to the nearest dwell position (d) was 1.4 cm (range 0.9-1.9). The median volume of the lumpectomy cavity receiving 32 Gy increased from 85.3% in the actual implant to 97.0% (range 74-100%) by increasing the dwell time of a single dwell position by a median factor (alpha) of 12.2 according to the above algorithm. With N = 3, the median proportion of the cavity volume receiving 32 Gy was improved to 97.5% (range 77-100%), with a median alpha of 5.7. Further improvement in lumpectomy cavity coverage was relatively small by increasing additional dwell times. In addition, with N = 20, the median absolute volume of breast tissue receiving 150% of the prescription dose was 70.3 cm3 compared to 26.3 cm3 in the actual implant; whereas with N = 1 or N = 3, this median volume was only 35.9 and 42.0 cm3, respectively.

CONCLUSION

Lumpectomy cavity coverage sometimes appears suboptimal with interstitial HDR breast brachytherapy using our current technique. A simple dwell-time increase at only 1-3 dwell positions can compensate for some underdosage without creating significant regions of overdosage. Using simple methodology, a single reference point representing the underdosed region can be utilized for initial selection of the dwell positions to be increased.

Impact of young age on outcome in patients with ductal carcinoma-in-situ treated with breast-conserving therapy

PURPOSE

We reviewed our institution's experience treating patients with ductal carcinoma-in-situ (DCIS) with breast-conserving therapy (BCT) to determine the impact of patient age on outcome.

PATIENTS AND METHODS

From 1980 to 1993, 146 patients were treated with BCT for DCIS. All patients underwent excisional biopsy, and 64% underwent re-excision. All patients received whole-breast irradiation to a median dose of 45 Gy. Ninety-four percent of patients received a boost to the tumor bed, for a median total dose of 60.4 Gy. All slides on every patient were reviewed by one pathologist. The median follow-up period was 7.2 years.

RESULTS

Seventeen patients developed an ipsilateral local recurrence, for 5- and 10-year actuarial rates of 10.2% and 12.4%, respectively. The 10-year rate of ipsilateral failure was 26.1% in patients younger than 45 years of age versus 8.6% in older patients (P =.03). On multivariate analysis, young age was independently associated with recurrence of the index lesion (true recurrence/marginal miss ¿TR/MM failures), regardless of how it was analyzed (eg, < 45 years of age or as a continuous variable). In addition, young patients had a dramatically higher 10-year rate of invasive TR/MM failures (19.9% v 3.2%). In a separate multivariate analysis for the development of invasive TR/MM failures, only patient age and predominant nuclear grade were independently associated with recurrence. The relationship between excision volume and outcome was analyzed in the 95 patients who underwent re-excision. The 5-year actuarial rate of TR/MM failure was significantly worse only in young patients with smaller (< 40 mL) re-excision volumes (33.3% v 9.1%; P =.02). In a separate multivariate analysis of only these 95 patients (25 of whom were < 45 years of age), the volume of re-excision had the strongest association with outcome (P =.05). Patient age was no longer associated with local recurrence.

CONCLUSION

These findings suggest that young patients with DCIS have a significantly greater risk of local recurrence after BCT that is independent of other previously defined risk factors. Our data also suggest that the extent of resection may in part be related to the less optimal results that are observed in these patients.

Defining biochemical cure for prostate carcinoma patients treated with external beam radiation therapy

BACKGROUND

The authors retrospectively reviewed their institution's long term experience with conventional external beam radiation therapy (RT) for localized prostate carcinoma to identify criteria associated with long term biochemical cure.

METHODS

Between January 1987 and December 1994, 871 patients were treated with external beam RT alone for clinically localized prostate carcinoma at William Beaumont Hospital, Royal Oak, Michigan. All patients received only external beam RT to a median total dose of 66.6 grays (Gy) (range, 59.4-70.4 Gy). No patient received hormonal therapy unless treatment failure was documented. The median follow-up was 5.0 years (range, 0. 2-11.8 years). Biochemical failure was defined according to the American Society for Therapeutic Radiology and Oncology Consensus Panel definition.

RESULTS

In the entire study group, 380 patients experienced biochemical failure at a median interval of 1.5 years after the completion of RT. The 5-year and 7-year actuarial rates of biochemical control were 50% and 48%, respectively. On multivariate analysis, a higher pretreatment prostate specific antigen (PSA) level, higher Gleason score, higher clinical T classification, higher nadir level, and shorter time interval to nadir all were associated significantly with biochemical failure (P < 0.001). The median intervals to biochemical failure for patients with pretreatment PSA levels </= 3.9 ng/mL, 4.0-19.9 ng/mL, and >/= 20.0 ng/mL were 2.2 years, 1.5 years, and 1.2 years, respectively (P < 0. 001). The median intervals to biochemical failure for patients with Gleason scores of 2-4, 5-7, and 8-10 were 1.8 years, 1.5 years, and 1.1 years, respectively (P < 0.001). Only 6 patients failed beyond 5 years after treatment even though 136 patients were at risk for failure beyond this point. When restricting analysis to 643 patients (74%) with >/= 3 years of PSA follow-up, the median nadir level for biochemically controlled patients was 0.6 ng/mL and occurred at a median interval of 1.9 years after RT versus a median nadir level of 1.3 ng/mL (P = 0.002) occurring at a median interval of 1.0 years (P < 0.001) in those patients who experienced biochemical failure. Patients were divided into subgroups based on their PSA nadir level and time to nadir. The 5-year actuarial biochemical control rates for patients with nadir values of </= 0.4 ng/mL, 0.5-0.9 ng/mL, 1. 0-1.9 ng/mL, 2.0-3.9 ng/mL, and >/= 4.0 ng/mL were 78%, 60%, 50%, 20%, and 9%, respectively (P < 0.001). The 5-year actuarial biochemical control rates for patients who reached their nadir at < 1.0 years, 1.0-1.9 years, 2.0-2.9 years, and >/= 3.0 years were 30%, 52%, 64%, and 92%, respectively (P < 0.001). All 52 patients who achieved a nadir of </= 0.4 ng/mL and required >/= 2.0 years to reach this nadir had biochemically controlled disease.

CONCLUSIONS

These results suggest that a patient has a high likelihood of biochemical cure after treatment for prostate carcinoma with conventional doses of external beam RT if he has not demonstrated biochemical failure within 5 years of treatment. Patients with lower pretreatment PSA levels and lower Gleason scores may require longer follow-up than those with less favorable characteristics to achieve the same certainty of cure. Patients who achieve a PSA nadir </= 0.4 ng/mL and require >/= 2.0 years to reach this nadir have the highest probability of cure.

The importance of adequate follow-up in defining treatment success after external beam irradiation for prostate cancer

PURPOSE

We reviewed our institution's experience treating patients with localized prostate cancer with external beam radiation therapy (RT) to determine how differences in the length of follow-up affect the determination of treatment outcome using the American Society for Therapeutic Radiology and Oncology (ASTRO) Consensus Panel Definition of biochemical failure (BF).

METHODS AND MATERIALS

From January 1987 through December 1997, 1109 patients with localized prostate cancer were treated with definitive external beam RT at William Beaumont Hospital, Royal Oak, Michigan. All patients received external beam RT to a median total prostate dose of 66.6 Gy (range: 59.4-70.4 Gy). A total of 1096 patients (99%) had sufficient prostate-specific antigen (PSA) follow-up to determine their biochemical status. To test the impact of differences in follow-up on the calculation of BF, 389 patients with at least 5 years of PSA follow-up were selected as the reference group for the initial analysis. BF was then retrospectively determined using the Consensus Panel definition at yearly intervals, ignoring the remainder of each patient's follow-up. The median follow-up for this group of patients was 6.6 years (range: 5.0-11.6 years). In a second analysis, patient cohorts were randomly selected with varying median PSA follow-up intervals in order to more accurately represent a population whose follow-up is distributed continuously over a defined range. Seven cohorts were randomly selected with 200 patients in each cohort. Cohorts were individually identified such that half of the patients (100) had 2 years or less follow-up than the stated time point for analysis and half (100) had up to 2 years more follow-up than the time point chosen for analysis. For example, in the cohort with a median follow-up of 3 years, 100 patients with a PSA follow-up from 1 to 3 years were randomly selected, and 100 patients with a follow-up from 3 to 5 years were randomly selected, thus generating a median follow-up of 3 years for this cohort (range: 1 to 5 years). This process was repeated five times for five random samples of seven cohorts each. Biochemical failure was calculated according to the Consensus Panel definition.

RESULTS

In the first analysis, significantly different rates of biochemical control (varying by 6-21%) were calculated for the same actuarial year chosen for analysis depending only upon the length of follow-up used. For example, the 3-year actuarial rate of biochemical control (BC) varied from 71% when calculated with 3 years of follow-up versus 50.4% with 7 years (p < 0.01). These differences in actuarial rates of BC were observed in all subsets of patients analyzed (e.g., PSA < 10, Gleason < or = 6, n = 132,p < 0.001; PSA < 10, Gleason > or = 7, n = 33, p = 0.03; PSA > or = 10, Gleason < or = 6, n = 109, p < 0.001; and PSA > or = 10, Gleason > or = 7, n = 72, p = 0.002). The absolute magnitude of the difference in actuarial rates of BC was greatest during years 2 (range 18-30%), 3 (range 16-25%), and 4 (range 15-24%) after treatment. In the second analysis using median PSA follow-ups (as defined above), statistically significant differences in actuarial rates of BC were again observed. For example, the 3-year actuarial rate of BC varied from 74.8% with a median follow-up of 2 years versus 49.2% with a median follow-up of 6 years. These dramatic differences in BC were still observed beyond 5 years.

CONCLUSION

When the ASTRO Consensus Panel definition of BF is used to calculate treatment success with external beam RT for prostate cancer, adequate follow-up is critical. Depending upon the length of time after treatment, significantly different rates of BC (varying by 15% to 30%) can be calculated for the same time interval chosen for analysis. These results suggest that data should only be reported if the length of follow-up extends at least beyond the time point at which actuarial results are examined for the majority of patients.

Dose-volume analysis for quality assurance of interstitial brachytherapy for breast cancer

PURPOSE/OBJECTIVE

The use of brachytherapy in the management of breast cancer has increased significantly over the past several years. Unfortunately, few techniques have been developed to compare dosimetric quality and target volume coverage concurrently. We present a new method of implant evaluation that incorporates computed tomography-based three-dimensional (3D) dose-volume analysis with traditional measures of brachytherapy quality. Analyses performed in this fashion will be needed to ultimately assist in determining the efficacy of breast implants.

METHODS AND MATERIALS

Since March of 1993, brachytherapy has been used as the sole radiation modality after lumpectomy in selected protocol patients with early-stage breast cancer treated with breast-conserving therapy. Eight patients treated with high-dose-rate (HDR) brachytherapy who had surgical clips outlining the lumpectomy cavity and underwent computed tomography (CT) scanning after implant placement were selected for this study. For each patient, the postimplant CT dataset was transferred to a 3D treatment planning system. The lumpectomy cavity, target volume (lumpectomy cavity plus a 1-cm margin), and entire breast were outlined on each axial slice. Once all volumes were entered, the programmed HDR brachytherapy source positions and dwell times were imported into the 3D planning system. Using the tools provided by the 3D planning system, the implant dataset was then registered to the visible implant template in the CT dataset. The distribution of the implant dose was analyzed with respect to defined volumes via dose-volume histograms (DVH). Isodose surfaces, the dose homogeneity index, and dosimetric coverage of the defined volumes were calculated and contrasted. All patients received 32 Gy to the entire implanted volume in 8 fractions of 4 Gy over 4 days.

RESULTS

Three-plane implants were used for 7 patients and a two-plane implant for 1 patient. The median number of needles per implant was 16.5 (range 11-18). Despite visual verification by the treating physician that surgical clips (with an appropriate margin) were within the boundaries of the implant needles, the median proportion of the lumpectomy cavity that received the prescribed dose was only 87% (range 73-98%). With respect to the target volume, a median of only 68% (range 56-81%) of this volume received 100% of the prescribed dose. On average, the minimum dose received by at least 90% of the target volume was 22 Gy (range 17.3-26.9), which corresponds to 69% of the prescribed dose.

CONCLUSION

Preliminary results using our new technique to evaluate implant quality with CT-based 3D dose-volume analysis appear promising. Dosimetric quality and target volume coverage can be concurrently analyzed, allowing the possibility of evaluating implants prospectively. Considering that target volume coverage may be suboptimal even after radiographically verifying accurate implant placement, techniques similar to this need to be developed to ultimately determine the true efficacy of brachytherapy in the management of breast cancer.

Pathologic and technical considerations in the treatment of ductal carcinoma in situ of the breast with lumpectomy and radiation therapy

BACKGROUND

Lumpectomy and radiation therapy is considered a standard treatment option for ductal carcinoma in situ (DCIS) of the breast. The incidence of locally recurrent carcinoma using this therapeutic approach ranges from 6%-19%. Multiple studies have attempted to identify factors associated with the development of local recurrences in these patients. Despite extensive reports examining this issue, no factor(s) has consistently been correlated with outcome.

METHODS

This review examines the criteria that various authors have proposed as being associated with recurrence, including DCIS grade, size, histologic subtype, status of surgical margins, and technical factors to help clarify their roles in optimizing treatment outcome. The issue of the definition of the type of recurrence is also addressed.

RESULTS

Though multiple studies have examined the impact of grade, histologic subtype, necrosis, and DCIS size on outcome, no consistent results have been observed to suggest that these factors can be routinely used to guide therapy. The adequacy of excision appears to correlate with local control but is imprecisely defined by margin status alone. Based upon recent data, it appears that atypical ductal hyperplasia and cancerization of lobules in the context of coexistent DCIS, may need to be considered as part of the DCIS lesion that should be excised. This issue may account for some of the disparate results of different studies of DCIS. For statistical purposes, recent studies also suggest that only recurrences developing within or adjacent to the bed of the initial DCIS lesion should be considered when analyzing factors associated with outcome. Recurrences developing elsewhere in the breast may include new DCIS and invasive lesions that bear no biologic relationship with the initial DCIS lesion. Finally, since it is impossible to insure that all DCIS has been removed, it may be more appropriate to consider DCIS lesions as adequately or inadequately excised instead of completely or incompletely excised. Since DCIS is essentially a microscopic disease, pathologists should have a primary role in helping to define the adequacy of excision.

CONCLUSIONS

Additional studies with complete pathology review and longer follow-up are needed to reach a consensus on which prognostic factors are consistently associated with recurrence for patients with DCIS treated with lumpectomy and radiation therapy. At the present time, adequacy of excision appears to correlate with outcome. However, more precise and consistent methods need to be developed to assist in the determination of adequate DCIS extirpation.

Treatment outcome with adjuvant and salvage irradiation after radical prostatectomy for prostate cancer

OBJECTIVES

To determine the factors associated with outcome by reviewing our institution's experience treating patients with external beam radiation therapy (RT) after radical prostatectomy.

METHODS

Sixty-one patients received RT to the prostatic fossa after radical prostatectomy for prostate cancer (median dose 59.4 Gy). Thirty-eight patients received adjuvant RT within 6 months of surgery for adverse pathologic findings only. Therapeutic RT was administered to 23 patients either for a persistently elevated postoperative prostate-specific antigen (PSA) level (n = 2), a rising PSA level more than 6 months after surgery (n = 9), or a biopsy-proven local recurrence (n = 12). Preoperative and preradiation PSA values, Gleason score, pathologic findings, patient age, total RT dose, and indication for RT were analyzed for their impact on biochemical control. The median follow-up was 48 months.

RESULTS

Patients treated with adjuvant RT achieved 3 and 5-year biochemical control rates of 84% and 67%, respectively. Multiple clinical, pathologic, and treatment-related factors were analyzed for an association with biochemical control. No variable was associated with 5-year outcome. The 5-year actuarial rate of biochemical control for patients treated with therapeutic RT was 16%. Multiple clinical, pathologic, and treatment-related factors were analyzed for an association with biochemical control. Only a pre-RT PSA level of 2 ng/mL or less was associated with an improved rate of biochemical control at 3 years (80% versus 27%, P = 0.001). However, at 5 years, this difference was not statistically significant. A separate analysis was performed to determine the prognostic factors associated with outcome for the entire group of patients. Only the indication for RT (adjuvant versus therapeutic) was associated with 5-year outcome. Patients treated with adjuvant RT had a statistically significant improvement in 5-year actuarial rates of biochemical control (67% versus 16%, P <0.001) and disease-free survival (66% versus 46%, P = 0.037) but not in overall survival. There were no statistically significant differences between patient groups with respect to age, preoperative PSA, Gleason score, pathologic T stage, median follow-up, and total RT dose.

CONCLUSIONS

At our institution, patients treated with adjuvant RT after prostatectomy for adverse pathologic findings achieved excellent rates of biochemical control that were significantly better than that of similar patients treated therapeutically for persistent or rising PSA or clinical local recurrence.

Brachytherapy boost techniques for locally advanced prostate cancer

Brachytherapy boosts in combination with external-beam radiation therapy allow a highly conformal dose of radiation to be delivered to the prostate in a safe, efficient manner. Several types of brachytherapy boost techniques are used currently. Techniques based on transrectal ultrasound (TRUS) guidance clearly provide the most accurate method of radioactive source placement with reduced toxicity. Temporary implants employing remote afterloading systems with high-dose-rate (HDR) brachytherapy offer the added advantage of further optimizing dose distribution after needle placement. Novel brachytherapy programs using intraoperative real-time dosimetric analyses provide additional options for performing truly conformal dose escalation. Results with these newer boost techniques appear to be as good as or better than other forms of therapy in comparably staged patients. Until standardized methods of reporting treatment data are uniformly applied and longer follow-up is obtained with other treatment modalities, brachytherapy boosts combined with external-beam radiation should be considered an acceptable treatment option for patients with locally advanced prostate cancer. The challenge for the future will be to determine which treatment approach is optimal given certain critical pretreatment prognostic factors. In addition, the role of adjuvant androgen deprivation in controlling this malignancy will be critical and awaits the results of several recently initiated or completed randomized trials.