Toxicity Associated With Postoperative Radiation Therapy for Prostate Cancer

Preliminary Evaluation of PTV Margins for Online Adaptive Radiation Therapy of the Prostatic Fossa

PURPOSE

In modern trials, traditional planning target volume (PTV) margins for postoperative prostate radiation therapy have been large (7-10 mm) to account for both daily changes in patient positioning and target deformation. With daily adaptive radiation therapy, these interfractional changes could be minimized, potentially reducing the margins required for treatment and improving adjacent normal-tissue dosimetry.

METHODS AND MATERIALS

A single-center retrospective study was conducted from March 2021 to November 2021. Patients receiving conventionally fractionated postoperative radiation therapy (PORT) for prostate cancer with pretreatment and posttreatment cone beam computed tomography (CBCT) imaging (pre-CBCT and post-CBCT, respectively) were included (248 paired images). Pretreatment and posttreatment clinical target volumes (pre-CTVs and post-CTVs) were contoured by a single observer on all CBCTs and verified by a second observer. Motion was calculated from pre-CTV to that of the post-CTV, and predicted margins were calculated with van Herk's formula. Adequate coverage of the proposed planning target volume (PTV) margin expansions (pre-PTV) were verified by determining overlap with post-CTV. In a smaller cohort (25 paired images), dosimetric changes with the proposed online adaptive margins were compared with conventional plans in the Ethos emulator environment.

RESULTS

The estimated margins predicted to achieve ≥95% CTV coverage for 90% of the population were 1.6 mm, 2.0 mm, and 2.2 mm (x-, y-, and z -xes, respectively), with 95% of the absolute region of interest displacement being within 1.9 mm, 2.8 mm, and 2.1 mm. After symmetrically expanding all pre-CTVs by 3 mm, the percentage of paired images achieving ≥95% CTV coverage was 97.1%. When comparing adaptive plans (3-mm margins) with scheduled plans (7-mm margins), rectum dosimetry significantly improved, with an average relative reduction in V40Gy[cc] of 59.2% and V65Gy[cc] of 79.5% (where V40Gy and V65Gy are defined as the volumes receiving 40 Gy and 65 Gy or higher dose, respectively).

CONCLUSIONS

Online daily adaptive radiation therapy could significantly decrease PTV margins for prostatic PORT and improve rectal dosimetry, with a symmetrical expansion of 3 mm achieving excellent coverage in this cohort. These results need to be validated in a larger prospective cohort.

Identification of patients at risk for biochemical recurrence after radical prostatectomy with intra-operative frozen section

OBJECTIVE

To identify patients at risk for biochemical recurrence (BCR) of prostate cancer (PCa) after radical prostatectomy (RP) with intra-operative whole-mount frozen section (FS) of the prostate.

MATERIAL AND METHODS

We examined differences in BCR between patients with initial negative surgical margins at FS, patients with final negative surgical margins with initial positive margins at FS without residual PCa after secondary tumour resection, and patients with final negative surgical margins with initially positive margins at FS with residual PCa in the secondary tumour resection specimen. Institutional data of 883 consecutive patients undergoing RP were collected. Intra-operative whole-mount FS was routinely used to check for margin status and, if necessary, to resect more periprostatic tissue in order to achieve negative margins. Patients with lymph node-positive disease or final positive surgical margins were excluded from the analysis. Kaplan-Meier curves and multivariable Cox proportional hazards regression analyses adjusting for clinical covariates were employed to examine differences in biochemical recurrence-free survival (BRFS) according to the resection status mentioned above.

RESULTS

The median follow-up was 22.4 months. The 1- and 2-year BRFS rates in patients with (81.0% and 72.9%, respectively; P = 0.001) and without residual PCa (90.3% and 82.3%, respectively; P = 0.033) after secondary tumour resection were significantly lower compared to patients with initial R0 status (93.4% and 90.9%, respectively). On multivariable Cox regression only residual PCa in the secondary tumour resection was associated with a higher risk of BCR compared to initial R0 status (hazard ratio 1.99, 95% confidence interval 1.01-3.92; P = 0.046).

CONCLUSION

Despite being classified as having a negative surgical margin, patients with residual PCa in the secondary tumour resection specimen face a high risk of BCR. These findings warrant closer post-RP surveillance of this particular subgroup. Further research of this high-risk subset of patients should focus on examining whether these patients benefit from early salvage therapy and how resection status impacts oncological outcomes in the changing landscape of PCa treatment.

Testing the Assessment of New Radiation Oncology Technology and Treatments framework using the evaluation of post-prostatectomy radiotherapy techniques

INTRODUCTION

We tested the ability of the Assessment of New Radiation Oncology Technology and Treatments framework to determine the clinical efficacy and safety of intensity-modulated radiation therapy (IMRT) compared with 3-dimensional radiation therapy (3DCRT) for post-prostatectomy radiation therapy (PPRT) to support its timely health economic evaluation.

METHODS

Treatment plans produced using FROGG guidelines provided dosimetry parameters for both techniques at 64 Gy and 70 Gy and were also used to model early and late outcome probabilities. Clinical parameters were derived from early toxicity and quality of life patient data, systematic literature review and expert opinion. Dosimetry parameters were correlated with the measures of clinical efficacy and safety.

RESULTS

Data from two patient cohorts (29 and 27 respectively) were collected within the project timeframe, providing evidence for acute toxicity and quality of life, and dosimetric comparisons. Relative rates of tumour control probability (TCP) and normal tissue control probability (NTCP) modelling were readily derived from the planning exercise and demonstrated advantages in uncomplicated TCP for IMRT over 3DCRT, predominantly due to normal tissue sparing. The safety of IMRT delivery was demonstrated with TCP uncompromised by IMRT protocol violations, which achieved rectal sparing only by reducing minimum target dose and coverage.

CONCLUSION

Sources of desk-top and patient-based evidence were successfully used to demonstrate potential improved clinical efficacy and safety of applying dose escalation using IMRT instead of 3DCRT in PPRT.

Acute anal toxicity after whole pelvic radiotherapy in patients with asymptomatic haemorrhoids: identification of dosimetric and patient factors

OBJECTIVE

Patients with asymptomatic haemorrhoids are known to be less tolerant of radiation doses lower than known tolerance doses. In the present study, the authors sought to identify the risk factors of acute haemorrhoid aggravation after whole pelvic radiotherapy (WPRT).

METHODS

The records of 33 patients with cervical, rectal or prostate cancer with asymptomatic haemorrhoids, which were confirmed by colonoscopy before the start of radiotherapy (RT), were reviewed. Acute anal symptoms, such as anal pain and bleeding, were observed up to 1 month after RT completion. Dosimetric and patient factors were analysed, and subgroup analyses were performed.

RESULTS

The median induction dose for acute anal symptoms was 34.1 Gy (range, 28.8-50.4 Gy). Post-operative treatment intent showed more acute anal toxicity of patient factors (p = 0.04). In subgroup analysis, post-operative treatment intent and concurrent chemoradiotherapy were found to be related to acute anal symptoms (p < 0.01). Of the dosimetric factors, V10 tended to be related to acute anal symptoms (p = 0.08).

CONCLUSION

This study indicates that asymptomatic haemorrhoid may deteriorate after low-dose radiation and that patient factors, such as treatment intent and concurrent chemotherapy, probably influence anal toxicity. In patients with asymptomatic haemorrhoids, WPRT requires careful dosimetry and clinical attention.

ADVANCES IN KNOWLEDGE

The tolerance of anal canal tends to be ignored in patients with pelvic cancer who are undergoing WPRT. However, patients with asymptomatic haemorrhoids may be troubled by low radiation doses, and further studies are required.

The anal canal as a risk organ in cervical cancer patients with hemorrhoids undergoing whole pelvic radiotherapy

AIMS AND BACKGROUND

Tolerance of the anal canal tends to be ignored in patients with cervical cancer undergoing whole pelvic radiotherapy. However, patients with hemorrhoids may be troubled with low radiation dose. We tried to analyze the dose-volume statistics of the anal canal in patients undergoing whole pelvic radiotherapy.

METHODS

The records of 31 patients with cervical cancer who received definite or postoperative radiotherapy at one institution were reviewed. Acute anal symptoms, such as anal pain and bleeding, were evaluated from radiotherapy start to 1 month after radiotherapy completion. Various clinical and dosimetric factors were analyzed to characterize relations with acute anal complications.

RESULTS

The anal verge was located an average of 1.2 cm (range -0.6~3.9) below the lower border of the ischial tuberosity and an average of 2.7 cm (range -0.6~5.7) behind the sacral promontory level. The presence of hemorrhoids before radiotherapy was found to be significantly associated with acute radiation-induced anal symptoms (p = 0.001), and the mean induction dose for anal symptoms was 36.9 Gy. No patient without hemorrhoids developed an anal symptom during radiotherapy. Dosimetric analyses of V30 and V40 showed marginal correlations with anal symptoms (p = 0.07).

CONCLUSIONS

The present study suggests a relation between acute anal symptoms following radiotherapy and acute hemorrhoid aggravation. Furthermore, the location of the anal verge was found to be variable, and consequently doses administered to the anal canal also varied substantially. Our results caution careful radiation treatment planning for whole pelvic radiotherapy, and that proper clinical management be afforded patients with hemorrhoids during radiotherapy.

Patient-reported outcomes after prostate cancer treatment

Objective:

Our aim was to understand patient-reported toxicities resulting from treatment of prostate cancer using various different modalities that have similar oncological endpoints.

Methods and materials:

An Internet-based survivorship care plan tool was used to collect patient-reported toxicity data for men who had undergone prostate cancer treatment.

Results:

A total of 127 users of the survivorship care plan tool reported to have been treated for prostate cancer. The median age of the patients at diagnosis in this group was 60 years (range = 25–74 years) and median time since diagnosis was 4 years (range 1–15 years); 61 (48%) received radiation as primary treatment, 44 (35%) received surgery as primary treatment and 22 (17%) received both surgery and radiation (adjuvant or salvage). Hormonal treatment was given to 50 (39%) patients. Some 15% (7/48) in the radiation group versus 50% (21/42) in the surgery group ( p < 0.001) developed urinary incontinence; 61% (33/54) in the radiation group and 86% (37/43) in the surgery group ( p = 0.02) reported having erectile dysfunction since treatment. Most users (84%) had not been offered a survivorship care plan previously.

Conclusion:

Men with prostate cancer experience significant urinary and sexual sequelae from treatment regardless of the modality used. Patients treated with surgery reported more urinary and sexual side effects than those treated with radiation. The majority of these men are not offered a survivorship care plan to deal with these long-term effects. Survivorship planning tools to assess such side effects and design long-term individualized plans are essential for all prostate cancer patients.

A decision model to estimate the cost-effectiveness of intensity modulated radiation therapy (IMRT) compared to three dimensional conformal radiation therapy (3DCRT) in patients receiving radiotherapy to the prostate bed

BACKGROUND

Intensity modulated radiation therapy (IMRT) is a radiation therapy technology that facilitates the delivery of an improved dose distribution with less dose to surrounding critical structures. This study estimates the longer term effectiveness and cost-effectiveness of IMRT in patients post radical prostatectomy.

METHODS

A Markov decision model was developed to calculate the incremental quality adjusted life years (QALYs) and costs of IMRT compared with three dimensional conformal radiation therapy (3DCRT). Costs were estimated from the perspective of the Australian health care system.

RESULTS

IMRT was both more effective and less costly than 3DCRT over 20 years, with an additional 20 QALYs gained and over $1.1 million saved per 1000 patients treated. This result was robust to plausible levels of uncertainty.

CONCLUSIONS

IMRT was estimated to have a modest long term advantage over 3DCRT in terms of both improved effectiveness and reduced cost. This result was reliant on clinical judgement and interpretation of the existing literature, but provides quantitative guidance on the cost effectiveness of IMRT whilst long term trial evidence is awaited.

Toxicity outcome in patients treated with modulated arc radiotherapy for localized prostate cancer

AIM

This study evaluates the acute toxicity outcome in patients treated with RapidArc for localized prostate cancer.

BACKGROUND

Modern technologies allow the delivery of high doses to the prostate while lowering the dose to the neighbouring organs at risk. Whether this dosimetric advantage translates into clinical benefit is not well known.

MATERIALS AND METHODS

Between December 2009 and May 2012, 45 patients with primary prostate adenocarcinoma were treated using RapidArc. All patients received 1.8 Gy per fraction, the median dose to the prostate gland, seminal vesicles, pelvic lymph nodes and surgical bed was 80 Gy (range, 77.4-81 Gy), 50.4 Gy, 50.4 Gy and 77.4 Gy (range, 75.6-79.2 Gy), respectively.

RESULTS

The time between the last session and the last treatment follow up was a median of 10 months (range, 3-24 months). The incidence of grade 3 acute gastrointestinal (GI) and genitourinary (GU) toxicity was 2.2% and 15.5%, respectively. Grade 2 acute GI and GU toxicity occurred in 30% and 27% of patients, respectively. No grade 4 acute GI and GU toxicity were observed. Older patients (>median) or patients with V60 higher than 35% had significantly higher rates of grade ≥2 acute GI toxicity compared with the younger ones.

CONCLUSIONS

RapidArc in the treatment of localized prostate cancer is tolerated well with no Grade >3 GI and GU toxicities. Older patients or patients with higher V60 had significantly higher rates of grade ≥2 acute GI toxicity. Further research is necessary to assess definitive late toxicity and tumour control outcome.