Stereotactic Body Radiation Therapy: A Radiosurgery Society Guide to the Treatment of Localized Prostate Cancer Illustrated by Challenging Cases

Traditionally, external beam radiotherapy (EBRT) for localized prostate cancer (PCa) involved lengthy courses with low daily doses. However, advancements in radiation delivery and a better understanding of prostate radiobiology have enabled the development of shorter courses of EBRT. Ultrahypofractionated radiotherapy, administering doses greater than 5 Gy per fraction, is now considered a standard of care regimen for localized PCa, particularly for intermediate-risk disease. Stereotactic body radiotherapy (SBRT), a specific type of ultrahypofractionated radiotherapy employing advanced planning, imaging, and treatment technology to deliver in five or fewer fractions, is gaining prominence as a cost-effective, convenient, and safe alternative to longer radiotherapy courses. It is crucial to address practical considerations related to patient selection, fractionation scheme, target delineation, and planning objectives. This is especially important in challenging clinical situations where clear evidence for guidance may be lacking. The Radiosurgery Society endorses this case-based guide with the aim of providing a practical framework for delivering SBRT to the intact prostate, exemplified by two case studies. The article will explore common SBRT dose/fractionation schemes and dose constraints for organs-at-risk. Additionally, it will review existing evidence and expert opinions on topics such as SBRT dose escalation, the use of rectal spacers, the role of androgen deprivation therapy in the context of SBRT, SBRT in special patient populations (e.g., high-risk disease, large prostate, high baseline urinary symptom burdens, and inflammatory bowel disease), as well as new imaging-guidance techniques like Magnetic Resonance Imaging for SBRT delivery.

A Medicare Claims Analysis of Racial and Ethnic Disparities in the Access to Radiation Therapy Services

PURPOSE

Reduced access and utilization of radiation therapy (RT) is a well-documented healthcare disparity observed among racial and ethnic minority groups in the USA and a contributor to the inferior health outcomes observed among Black, Hispanic, and Native American patient groups. What is less understood are the points during the process of care following RT consultation at which patients either fail to complete their prescribed treatment or encounter delays. Identification of those points where significant differences exist among different patient groups may help identify opportunities to close gaps in the access of clinically indicated RT.

METHODS AND MATERIALS

This analysis examines 261,559 RT episodes abstracted from Medicare claims and beneficiary data between 2016 and 2018 to determine rates of treatment initiation following planning and timeliness of treatment completion for different racial groups.

RESULTS

Failure to initiate treatment was observed to be 29.3% relatively greater for Black, Hispanic, and Native American patients than for White and Asian patients. Among episodes for which treatment was initiated, Black and Hispanic patients were observed to require a significantly greater number of calendar days (when adjusted for fraction number) for completion than for White, Asian, and Native American patients.

CONCLUSIONS

There appears to be a patient cohort for which RT disparities may be more marginal in their effects-allowing for access to consultation and treatment prescription but not for treatment initiation or timely completion of treatment-and may therefore permit effective solutions to help address current differences in cancer outcomes.

An Overview of the Radiation Oncology Alternative Payment Model and Impact on Practices Serving Vulnerable Populations

Radiation oncology reimbursement methodology has been largely unchanged over the past 30 years, and new approaches are of great interest to practicing radiation oncologists and other health care stakeholders. Traditional radiation oncology reimbursement is based on a series of individual codes for evaluation and management (professional) and technical services, yielding a complex reimbursement system. In an attempt to move toward a simpler, episodic payment model, bundling all of the codes into a single payment, an alternative payment model for radiation oncology was developed. The radiation oncology alternative payment model is a revolutionary change in how radiation oncologic services will be reimbursed and has potential to affect all aspects of radiation oncologic care. Here, the authors review the origin of the currently proposed radiation oncology model and discuss potential implications of this model on the provision of care, especially as it relates to rural practices and other underserved and vulnerable patient populations.

Radiation Oncology's Place in Payment Reform: ASTRO Advocates for a Place at the Table

In its current form, the Radiation Oncology Model (RO Model) prioritizes payment cuts over true value-based payment transformation. With significant modifications to the payment methodology, the reporting requirements, and recognition of the unique challenges faced by disadvantaged populations, the RO Model can protect patient access to care, preserve the physician-patient decision-making process, and ensure the delivery of high-quality, efficient radiation therapy treatment. The American Society for Radiation Oncology has spent several years advocating for a meaningful alternative payment model for radiation oncology and continues to push The Center for Medicare and Medicaid Innovation for changes to the RO Model that will recognize these key outcomes.

Multicenter Trial of Stereotactic Body Radiation Therapy for Low- and Intermediate-Risk Prostate Cancer: Survival and Toxicity Endpoints

PURPOSE

The radiobiology of prostate cancer may favor the extreme hypofractionation inherent in stereotactic body radiation therapy (SBRT); however, data from a large multicenter study are lacking. We therefore examined the hypothesis that dose-escalated SBRT can be safely administered across multiple institutions, with favorable 5-year disease-free survival (DFS) rates compared with historical controls.

METHODS AND MATERIALS

Twenty-one centers enrolled 309 patients with prostate adenocarcinoma: 172 with low-risk (LR) and 137 with intermediate-risk (IR) disease. All were treated with a non-coplanar robotic SBRT platform using real-time tracking of implanted fiducials. The prostate was prescribed 40 Gy in 5 fractions of 8 Gy. We assessed toxicities using Common Terminology Criteria for Adverse Events (CTCAE) version 3 and biochemical failure using the "nadir + 2" definition. The study population yielded 90% power to identify excessive (>10%) rates of grade ≥3 genitourinary (GU) or gastrointestinal toxicities and, in the LR group, 80% power to show superiority in DFS over a 93% historical comparison rate.

RESULTS

At a median follow-up of 61 months, 2 LR patients (1.2%) and 2 IR patients (1.5%) experienced grade 3 GU toxicities, far below the 10% toxicity rate deemed excessive (upper limits of 95% confidence interval, 3.5% and 4.3%, respectively). No grade 4 or 5 toxicities occurred. All grade 3 toxicities were GU, occurring 11 to 51 months after treatment. For the entire group, the actuarial 5-year overall survival rate was 95.6% and the DFS rate was 97.1%. The 5-year DFS rate was 97.3% for LR patients (superior to the 93% DFS rate for historical controls; P = .0008; lower limit of 95% confidence interval, 94.6%) and 97.1% for IR patients.

CONCLUSIONS

Dose-escalated prostate SBRT was administered with minimal toxicity in this multi-institutional study. Relapse rates compared favorably with historical controls. SBRT is a suitable option for LR and IR prostate cancer.

Radiation oncology: a perspective on health reform and value-based initiatives

The American Society for Radiation Oncology Payment Reform Action Plan is a three-phased proactive plan to ensure predictable and fair reimbursement for radiation oncology treatment.

Radiotherapeutic and surgical management for newly diagnosed brain metastasis(es): An American Society for Radiation Oncology evidence-based guideline

Purpose

To systematically review the evidence for the radiotherapeutic and surgical management of patients newly diagnosed with intraparenchymal brain metastases.

Methods and Materials

Key clinical questions to be addressed in this evidence-based Guideline were identified. Fully published randomized controlled trials dealing with the management of newly diagnosed intraparenchymal brain metastases were searched systematically and reviewed. The U.S. Preventative Services Task Force levels of evidence were used to classify various options of management.

Results

The choice of management in patients with newly diagnosed single or multiple brain metastases depends on estimated prognosis and the aims of treatment (survival, local treated lesion control, distant brain control, neurocognitive preservation).

Single brain metastasis and good prognosis (expected survival 3 months or more): For a single brain metastasis larger than 3 to 4 cm and amenable to safe complete resection, whole brain radiotherapy (WBRT) and surgery (level 1) should be considered. Another alternative is surgery and radiosurgery/radiation boost to the resection cavity (level 3). For single metastasis less than 3 to 4 cm, radiosurgery alone or WBRT and radiosurgery or WBRT and surgery (all based on level 1 evidence) should be considered. Another alternative is surgery and radiosurgery or radiation boost to the resection cavity (level 3). For single brain metastasis (less than 3 to 4 cm) that is not resectable or incompletely resected, WBRT and radiosurgery, or radiosurgery alone should be considered (level 1). For nonresectable single brain metastasis (larger than 3 to 4 cm), WBRT should be considered (level 3).

Multiple brain metastases and good prognosis (expected survival 3 months or more): For selected patients with multiple brain metastases (all less than 3 to 4 cm), radiosurgery alone, WBRT and radiosurgery, or WBRT alone should be considered, based on level 1 evidence. Safe resection of a brain metastasis or metastases causing significant mass effect and postoperative WBRT may also be considered (level 3).

Patients with poor prognosis (expected survival less than 3 months): Patients with either single or multiple brain metastases with poor prognosis should be considered for palliative care with or without WBRT (level 3).

It should be recognized, however, that there are limitations in the ability of physicians to accurately predict patient survival. Prognostic systems such as recursive partitioning analysis, and diagnosis-specific graded prognostic assessment may be helpful.

Conclusions

Radiotherapeutic intervention (WBRT or radiosurgery) is associated with improved brain control. In selected patients with single brain metastasis, radiosurgery or surgery has been found to improve survival and locally treated metastasis control (compared with WBRT alone).

Predictors of response to sildenafil citrate following radiation therapy for prostate cancer

INTRODUCTION

Phosphodiesterase type 5 inhibitor (PDE5) use is a treatment strategy for prostate cancer patients with post-radiation therapy (RT) erectile dysfunction (ED).

AIM

To define the predictors of sildenafil response in men treated with RT for prostate cancer.

MAIN OUTCOME MEASURES

International Index of Erectile Function (IIEF).

METHODS

Patients were enrolled prospectively if they met the following criteria: (i) either a three-dimensional conformal external beam (EBRT) or brachytherapy (BT) with or without androgen deprivation (AD) for prostate cancer; (ii) self-reported ability to have sexual intercourse prior to RT; (iii) experienced onset of ED following RT; (iv) candidates for sildenafil citrate use; (v) followed-up periodically; and (vi) completed the IIEF at least 12 months after RT. Failure to respond to sildenafil was defined as IIEF-erectile function (EF) domain score of <22.

RESULTS

One hundred fifty-two patients met all the criteria: 110 in the EBRT group and 42 in the BT group. Mean age was 62 years. The mean follow-up was 38 months. Mean radiation dose for EBRT was 78 Gy and for BT was 101 Gy. Thirty-five patients received AD, 25% of EBRT, and 62% of BT patients. Sixty-one percent of the patients receiving AD had exposure only pre-RT, whereas 39% had pre- and post-RT AD exposure. The mean duration of AD was 4.6 months. Post-RT IIEF-EF domain score at >24 months was 17. Successful response to sildenafil occurred in 68% of men at 12 months after RT, 50% at 24 months, and 36% at 36 months. On multivariable analysis, predictors of failure to respond to sildenafil were: older age, longer time after RT, AD > 4 months duration, and RT dose > 85 Gy. Modality of radiation delivery was not predictive of sildenafil failure.

CONCLUSIONS

A steady decrease in sildenafil response was seen with increasing duration after RT. Several factors were predictive of sildenafil failure.

Feasibility of conditioning with thymoglobulin and reduced intensity TBI to reduce acute GVHD in recipients of allogeneic SCT

Murine studies using anti-T-cell antibodies for conditioning in allogeneic SCT demonstrate engraftment with low rates of GVHD. On the basis of this preclinical model, we conditioned 30 patients with advanced hematologic malignancies with rabbit antithymocyte globulin (ATG) and TBI, to reduce rates of fatal acute GVHD. Patients were enrolled in two sequential groups: cohort 1 received ATG 10 mg/kg in divided doses (days -4 to -1)+200 cGy TBI (n=16), and cohort 2 received ATG (days -10 to -7)+450 cGy TBI (n=14). Median donor blood chimerism for the combined group was 94, 93 and 93% in the first, second and third months after transplant. Only three developed grade II acute GVHD despite 43% of patients receiving unrelated donor transplants. One-year survival was 71+/-11 and 54+/-14%, respectively, in recipients of related and unrelated donor SCT. Donor lymphocyte infusions were needed in 12 patients for the management of relapse and for mixed donor-recipient chimerism in 4 patients. We conclude that 10 mg/kg ATG and TBI allows engraftment with a low risk of acute GVHD; however, further dose optimization of ATG is required to achieve a balance between GVHD and disease relapse.

Long-term follow-up of 111In-capromab pendetide (ProstaScint) scan as pretreatment assessment in patients who undergo salvage radiotherapy for rising prostate-specific antigen after radical prostatectomy for prostate cancer

PURPOSE

To evaluate the long-term failure patterns in patients who underwent an (111)In-capromab pendetide (ProstaScint) scan as part of their pretreatment assessment for a rising prostate-specific antigen (PSA) level after prostatectomy and subsequently received local radiotherapy (RT) to the prostate bed.

METHODS

Fifty-eight patients were referred for evaluation of a rising PSA level after radical prostatectomy. All patients had negative findings for metastatic disease after abdominal/pelvis imaging with CT and isotope bone scans. All patients underwent a capromab pendetide scan, and the sites of uptake were noted. All patients were treated with local prostate bed RT (median dose 66.6 Gy).

RESULTS

Of the 58 patients, 20 had biochemical failure (post-RT PSA level >0.2 ng/mL or a rise to greater than the nadir PSA), including 6 patients with positive uptake outside the bed (positive elsewhere). The 4-year biochemical relapse-free survival (bRFS) rates for patients with negative (53%), positive in the prostate bed alone (45%), or positive elsewhere (74%) scan findings did not differ significantly (p = 0.51). The positive predictive value of the capromab pendetide scan in detecting disease outside the bed was 27%. The capromab pendetide scan status had no effect on bRFS. Those with a pre-RT PSA level of <1 ng/mL had improved bRFS (p = 0.003).

CONCLUSION

The capromab pendetide scan has a low positive predictive value in patients with positive elsewhere uptake and the 4-year bRFS was similar to that for those who did not exhibit positive elsewhere uptake. Therefore, patients with a postprostatectomy rising PSA level should considered for local RT on the basis of clinicopathologic factors.

Androgen receptor levels are increased by interferons in human prostate stromal and epithelial cells

Proliferation of normal and malignant prostate epithelium is regulated by androgen stimulation via both the androgen receptor (AR)-positive stromal and epithelial cells. However, it is not known how AR expression is regulated in human prostate cells. We report that treatment of normal human prostate stromal cells (PrSCs) with type I IFN (alpha or beta), but not type II IFN (gamma), resulted in increased levels of AR protein. The maximal increase in AR protein levels was dependent on the dose and the duration of the IFN-alpha treatment. We found that the increase in AR protein levels was independent of de novo transcription and protein synthesis. Interestingly, the IFN-alpha treatment of PrSCs resulted in considerable nuclear accumulation of AR, stimulation of AR-mediated transcription of reporter genes, and retardation of cell proliferation. Furthermore, treatment of normal human prostate epithelial cells with IFNs (alpha, beta or gamma) also resulted in increased levels of AR protein. Together, our observations identify the androgen receptor as an IFN-regulated protein in normal human prostate stromal and epithelial cells and predict that IFN-induced levels of AR in prostate cells contribute to the regulation of androgen signaling.

The hemodynamics of erectile dysfunction following external beam radiation for prostate cancer

INTRODUCTION

Radiation to the pelvis is associated with erectile dysfunction (ED). The mechanisms include neural injury, vascular alterations, and corporal smooth structural changes. There exists little data on the vascular assessment of men who present with ED following radiation therapy for prostate cancer. This study was conducted to evaluate the erectile hemodynamics in such a patient population.

METHODS

Men who presented for the evaluation of ED following radiation therapy for prostate cancer underwent vascular evaluation in the form of dynamic infusion cavernosometry and cavernosography (DICC). Established parameters were recorded to define arterial insufficiency and venocclusive function including cavernosal artery occlusion pressure, flow-to-maintain, and pressure decay.

RESULTS

Sixteen men with a mean age of 61 years presenting with ED after radiation underwent DICC at a mean duration post radiation of 11 months. All of the patients in whom arterial hemodynamics were measurable had abnormal arterial parameters, and 85% had abnormal venocclusive parameters. Of the patients who could undergo cavernosography, 80% had venous leak, most commonly from the crura.

CONCLUSIONS

Men presenting with ED following radiation therapy for prostate cancer are likely to have significant alterations in erectile hemodynamics, often of a combined arterio-venogenic nature. In patients with venous leak the majority had venocclusive dysfunction with venous leak emanating from the crura.

Evidence-based review of three-dimensional conformal radiotherapy for localized prostate cancer: An ASTRO outcomes initiative

PURPOSE

To perform a systematic review of the evidence to determine the efficacy and effectiveness of three-dimensional conformal radiotherapy (3D-CRT) for localized prostate cancer; provide a clear presentation of the key clinical outcome questions related to the use of 3D-CRT in the treatment of localized prostate cancer that may be answered by a formal literature review; and provide concise information on whether 3D-CRT improves the clinical outcomes in the treatment of localized prostate cancer compared with conventional RT.

METHODS AND MATERIALS

We performed a systematic review of the literature through a structured process developed by the American Society for Therapeutic Radiology and Oncology's Outcomes Committee that involved the creation of a multidisciplinary task force, development of clinical outcome questions, a formal literature review and data abstraction, data review, and outside peer review.

RESULTS

Seven key clinical questions were identified. The results and task force conclusions of the literature review for each question are reported.

CONCLUSION

The technological goals of reducing morbidity with 3D-CRT have been achieved. Randomized trials and follow-up of completed trials remain necessary to address these clinical outcomes specifically with regard to patient subsets and the use of hormonal therapy.

Neoadjuvant Chemoradiotherapy for Locally Advanced Esophageal Cancer

HYPOTHESIS

Patients receiving neoadjuvant chemoradiotherapy followed by surgery (CRS) undergo downstaging of their tumor and have improved survival when compared with patients undergoing surgery followed by adjuvant chemoradiotherapy (SCR).

DESIGN

Retrospective study.

SETTING

Tertiary-care university medical center.

PATIENTS

One hundred twenty-three patients with squamous cell carcinoma and adenocarcinoma of the esophagus underwent Ivor-Lewis esophagectomy from January 1, 1990, through December 31, 2001. Of these, 31 received CRS; 27, SCR; and 65, surgery alone.

INTERVENTIONS

Patients were candidates for neoadjuvant or adjuvant therapy if they had locally advanced disease (T3/T4 N0 or any T stage with N1). Neoadjuvant and adjuvant therapies were nonrandomized and based on the preference of the treating oncologist and surgeon.

MAIN OUTCOME MEASUREMENTS

Pathological downstaging was analyzed in the patients receiving CRS. Operative mortality, postoperative morbidity, median survival, and overall survival were compared between the CRS and SCR groups.

RESULTS

Pathological downstaging (as characterized by TNM staging) was observed in 20 (64%) of the patients receiving CRS. Complete pathological responses occurred in 5 (16%) of the patients undergoing CRS. No 30-day mortality was observed in either treatment group. No statistical difference in survival was observed between groups, although a trend suggested improved survival with neoadjuvant therapy (3-year survival in CRS and SCR groups was 45% and 22%, respectively; P =.15). Complete pathological responders in the CRS group had a 1-year survival of 80% compared with 29% in nonresponders (P =.25). No statistical differences were observed between groups in relation to blood loss, length of hospital stay, mortality, or morbidity.

CONCLUSIONS

Neoadjuvant chemoradiotherapy effectively downstages cancer in patients with locally advanced esophageal disease. Morbidity and operative mortality were not significantly different between patients receiving neoadjuvant and adjuvant therapy. The difference in overall survival between the 2 groups did not reach statistical significance, although a trend at 3 years was observed.

Is an 192Ir permanent seed implant feasible for prostate brachytherapy?

PURPOSE

(125)I permanent seed brachytherapy for prostate cancer produces good clinical outcomes and limits radiation exposure to medical staff and patients' families. However, (125)I seeds cost thousands of dollars per implant. An encapsulated (192)Ir permanent seed possibly could cost less than 10 dollars. Could inexpensive permanent (192)Ir seeds be used for prostate implants?

METHODS AND MATERIALS

We review the radiobiology of permanent implants, calculate the (192)Ir permanent seed air kerma strength (activity) required, simulate (125)I and (192)Ir seed implants and mixtures thereof, calculate exposure rates near simulated (192)Ir prostate patients, calculate potential radiation exposure to medical staff and family members, review patient release regulations, and analyze the potential cost benefits of using (192)Ir permanent seed implants.

RESULTS

Low air kerma strength (<0.4 microGy m(2)/h/seed) [activity < 0.1-mCi/seed; <0.0558 mg Ra eq/seed] permanent (192)Ir seed implants yield more uniform prostate doses than (125)I seed implants and acceptable urethra, bladder, and rectal doses. The (192)Ir 73.83-day half-life allows mixing (192)Ir seeds and (125)I seeds.

CONCLUSIONS

We believe medical staff could safely implant 40 microGy m(2)/h [10-mCi; 5.58 mg Ra eq] (192)Ir per case. Occupancy factors (1/8, 1/16) could acceptably limit families' exposures. Seed costs could be reduced markedly. With adequate protection of medical staff and proper instructions to patients post-implant, low air kerma strength (<0.4 microGy m(2)/h/seed) [activity <0.1-mCi/seed; <0.0558 mg Ra eq/seed] (192)Ir permanent seed implants are feasible in large patients, with mixed ((125)I, (92)Ir) seed implants feasible for modest size patients. Such implants could be useful in populous countries (China, India, Brazil) and for others who find (125)I seed implants too expensive to perform.

Assessment of different IMRT boost delivery methods on target coverage and normal-tissue sparing

PURPOSE

Because of biologic, medical, and sometimes logistic reasons, patients may be treated with 3D conformal therapy or intensity-modulated radiation therapy (IMRT) for the initial treatment volume (PTV(1)) followed by a sequential IMRT boost dose delivered to the boost volume (PTV(2)). In some patients, both PTV(1) and PTV(2) may be simultaneously treated by IMRT (simultaneous integrated boost technique). The purpose of this work was to assess the sequential and simultaneous integrated boost IMRT delivery techniques on target coverage and normal-tissue sparing.

MATERIALS AND METHODS

Fifteen patients with head-and-neck (H&N), lung, and prostate cancer were selected for this comparative study. Each site included 5 patients. In all patients, the target consisted of PTV(1) and PTV(2). The prescription doses to PTV(1) and PTV(2) were 46 Gy and 66 Gy (H&N cases), 45 Gy and 66.6 Gy (lung cases), 50 Gy and 78 Gy (prostate cases), respectively. The critical structures included the following: spinal cord, parotid glands, and brainstem (H&N structures); spinal cord, esophagus, lungs, and heart (lung structures); and bladder, rectum, femurs (prostate structures). For all cases, three IMRT plans were created: (1) 3D conformal therapy to PTV(1) followed by sequential IMRT boost to PTV(2) (sequential-IMRT(1)), (2) IMRT to PTV(1) followed by sequential IMRT boost to PTV(2) (sequential-IMRT(2)), and (3) Simultaneous integrated IMRT boost to both PTV(1) and PTV(2) (SIB-IMRT). The treatment plans were compared in terms of their dose-volume histograms, target volume covered by 100% of the prescription dose (D(100%)), and maximum and mean structure doses (D(max) and D(mean)).

RESULTS

H&N cases: SIB-IMRT produced better sparing of both parotids than sequential-IMRT(1), although sequential-IMRT(2) also provided adequate parotid sparing. On average, the mean cord dose for sequential-IMRT(1) was 29 Gy. The mean cord dose was reduced to approximately 20 Gy with both sequential-IMRT(2) and SIB-IMRT. Prostate cases: The volume of rectum receiving 70 Gy or more (V(>70 Gy)) was reduced to 18.6 Gy with SIB-IMRT from 22.2 Gy with sequential-IMRT(2). SIB-IMRT reduced the mean doses to both bladder and rectum by approximately 10% and approximately 7%, respectively, as compared to sequential-IMRT(2). The mean left and right femur doses with SIB-IMRT were approximately 32% lower than obtained with sequential-IMRT(1). Lung cases: The mean heart dose was reduced by approximately 33% with SIB-IMRT as compared to sequential-IMRT(1). The mean esophagus dose was also reduced by approximately 10% using SIB-IMRT as compared to sequential-IMRT(1). The percentage of the lung volume receiving 20 Gy (V(20 Gy)) was reduced to 26% by SIB-IMRT from 30.6% with sequential-IMRT(1).

CONCLUSIONS

For equal PTV coverage, both sequential-IMRT techniques demonstrated moderately improved sparing of the critical structures. SIB-IMRT, however, markedly reduced doses to the critical structures for most of the cases considered in this study. The conformality of the SIB-IMRT plans was also much superior to that obtained with both sequential-IMRT techniques. The improved conformality gained with SIB-IMRT may suggest that the dose to nontarget tissues will be lower.

Second primary cancers in patients with laryngeal cancer: a population-based study

BACKGROUND

Literature regarding incidence of site-specific second cancers after laryngeal cancer is limited. Risk factors associated with second primaries are unknown.

METHODS

Second primaries after laryngeal cancer in the SEER database (1973-1996) were analyzed for incidence, relative risk compared with the general population, and potential risk factors, including radiotherapy. Information on chemotherapy and tobacco smoking was not available in the SEER database.

RESULTS

Of 20,074 laryngeal cancer patients surviving at least 3 months, 3533 (17.6%) developed second cancers. The cumulative risk of developing a second cancer was 26% at 10 years and 47% at 20 years. Compared with age-adjusted, gender, and tumor-specific rates in the general population, laryngeal cancer patients had higher risks of second cancers overall (observed-to-expected ratio [O/E] = 1.68, 95% confidence interval [CI] = 1.58-1.79), head-and-neck (4.81 [4.31-5.58]), esophageal (3.99 [3.29-4.83]), and lung (3.56 [3.34-3.79]) cancer. Advanced age at initial diagnosis was associated with increased risks of second cancers (p = 0.0001). Radiotherapy was associated with increased risk of second cancers overall (relative risk [RR] = 1.10 [1.02-1.18], p = 0.012), especially second cancers of the lung (RR = 1.18, [1.05-1.33], p = 0.006) and possibly second cancers of the head and neck (RR = 1.26, [0.99-1.60], p = 0.061). Radiotherapy was associated with a 68% excess risk (RR = 1.68, [1.16-2.43], p = 0.007) of developing a second head-and-neck cancer in patients who survived more than 5 years. Second primary was associated with a poor survival (p = 0.0001).

CONCLUSIONS

Second cancers after laryngeal cancer are common, especially for long-term survivors. Radiotherapy was associated with a small increased risk of developing second cancers overall and long-term risk of head-and-neck cancers. This data should be interpreted with caution in light of the lack of information on chemotherapy and tobacco smoking in the SEER database. Prevention and early detection are indicated.

Role of IMRT in reducing penile doses in dose escalation for prostate cancer

PURPOSE

In three-dimensional conformal radiotherapy (3D-CRT), penile tissues adjacent to the prostate are exposed to significant doses of radiation. This is likely to be a factor in development of posttreatment erectile dysfunction. In this study, we investigate whether intensity-modulated radiation therapy (IMRT) leads to lower radiation exposure to proximal penile tissues (PPT) when compared with 3D-CRT.

MATERIALS AND METHODS

Ten randomly selected patients with clinically localized prostate cancer constituted the study group. Using identical structure sets, 3D-CRT and IMRT plans were designed for each patient. For IMRT, both tomographic (TOMO) and step-and-shoot (SS) techniques were used. Treatment plans were developed using 18 MV photons for 3D-CRT, 6 MV photons for TOMO, and 6 MV and 18 MV photons for SS plans. The PPT up to the beginning of the penile shaft (usually measuring 2-3 cm) was outlined by a team composed of a board-certified urologist and a radiation oncologist. The outlined PPT was subdivided into three segments (P1, P2, P3), and the radiation dose to each segment and to the entire structure was calculated. In addition, PPT was subdivided into corporal cavernosa (CC) and corpus spongiosum (bulb). The prostate dose was escalated from 73.8 Gy to 81 Gy to 90 Gy. Target D(95) (dose to 95% volume), critical structure D(5) (dose to 5% volume), and D(mean) (mean dose) were used in the comparison among treatment plans. Because 3D-CRT uses larger field margins than does IMRT, target and critical structure doses were recalculated in 3D-CRT plans employing field margins obtained from IMRT plans. Planning target volumes in original and modified 3D-CRT plans were the same.

RESULTS

Compared with 3D-CRT plans, the mean PPT doses were reduced by 40.2%, 43.6%, and 46.2%, respectively, at the three prescription dose levels in TOMO plans. The average D(mean) for CC was lower by 46.4%, 48.4%, and 51.4%, whereas the average bulb D(mean) was reduced by 44.2%, 44.9%, and 47.9%, respectively. There was also considerable sparing of P1, with a reduction in average D(mean) of 41.9%, 45.5%, and 48.5% compared with 3D-CRT. All differences between 3D-CRT and IMRT doses were statistically significant (p < 0.001). Similar improvements were noticed in maximum doses (D(5)) for penile structures. The percent dose reduction with IMRT plans improved as prostate dose was escalated. When compared with 3D-CRT plans with reduced fields, IMRT plans showed slightly smaller but still significant improvements in critical structure doses (p < 0.001). Compared with SS plans, TOMO plans produced improved sparing of dose to critical structures.

CONCLUSIONS

IMRT allows for dose escalation in prostate cancer while keeping penile tissue doses significantly lower compared to conformal radiotherapy. This may result in improved potency rates over current results observed with 3D-CRT.

Effect of prostatic edema on CT-based postimplant dosimetry

PURPOSE

To investigate the magnitude of edema after prostate brachytherapy and its effect on the CT-based postimplant dosimetry based on the sequential CT scans using dose-volume histograms, dose conformity, and homogeneity indices in patients with prostate cancer.

METHODS AND MATERIALS

CT scans were obtained for 25 patients who underwent prostate brachytherapy with 125I or 103Pd before implant and postimplant Day 1, Day 7, and Day 28. The prostate, rectum, and bladder volumes on each scan were contoured by the same physician. Posttreatment dose distributions were generated using FOCUS (CMS Inc., St. Louis, MO) brachytherapy planning software. Dose calculations were based on TG43 formalism. Dose-volume histograms for target, rectum, and bladder were created for all patients, and the quality of the implants was analyzed using the dose conformity indices: CT-based target volumes ratios, TVR(1) and TVR(2); dose homogeneity indices, DHI(1), DHI(2), and DNR; dose coverage index, CI; the percentage of the prostate volume enclosed by 100%, 90%, and 80% of the prescription dose: V(100), V(90), and V(80); the volume of the rectum covered by 100%, 80%, and 70% of the prescription dose; and the dose covering 90% of the prostate volume (D(90)).

RESULTS

The prostate volume increased between the prescan and the implant Day 1 scans and then decreased between Day 1 and Day 28 scans. The average increase in prostate volume was 30% between the prescan and implant Day 1 scans for the 25 cases evaluated. The prostate volume decreased 20% between the Day 1 and Day 28 scans. The preplan dose coverage to the periphery of the prostate was 100% for all cases evaluated. V(100) increased from an average of 77% to 85% between the Day 1 and Day 28 scans, respectively. On average, D(90) increased from 84% for Day 1 to 93% for Day 28. The average TVR(1), TVR(2), and CI were 1.99, 2.28, and 0.87, respectively, based on the Day 28 scans. The average DHI(1), DHI(2), and DNR were 0.52, 0.46, and 0.48, respectively, based on the Day 28 scans.

CONCLUSIONS

The decrease in prostate volume from Day 1 to Day 28 after the implant markedly improved the prescription dose covering the prostate from 77% to 85%. Day 28 prostate volumes were still about 10% larger than the preimplant CT volumes for the 25 cases evaluated. Postimplant dosimetry using dose conformity and homogeneity indices is dependent on the timing of CT studies, as a result of changing prostate volumes from edema.

Radiation exposure to the corporeal bodies during 3-dimensional conformal radiation therapy for prostate cancer

PURPOSE

Radiation therapy for prostate cancer is associated with the development of post-treatment erectile dysfunction. Use of 3-dimensional (D) conformal delivery techniques has reduced delivery of radiation to periprostatic tissues. However, the exact magnitude of radiation that the corporeal bodies are exposed to using this delivery technique is currently unknown. This study was undertaken to calculate the radiation dose delivered to the corporeal bodies during 3-D conformal radiotherapy.

MATERIALS AND METHODS

Ten patients with proven prostate adenocarcinoma who underwent pre-therapy computerized tomography simulation and radiation delivery planning had the proximal corporeal bodies outlined on axial computerized tomography. The dose to the proximal penile tissues was then calculated using computer modeling.

RESULTS

The total dose of radiation administered to the prostate and seminal vesicles was 73.8 Gy. Mean radiation delivered to the most proximal 2 cm. of the corporeal bodies was 31 +/- 12.8 Gy., equating to 43% of the total dose of radiation delivered to the prostate and seminal vesicles.

CONCLUSIONS

These data indicate that large doses of radiation are being delivered to erectile tissue in the proximal penis despite careful pretreatment planning for 3-D conformal radiation therapy for prostate cancer. These data should encourage the development of radiation delivery strategies that minimize corporeal tissue exposure.

Radiation exposure to the corporeal bodies during 3-dimensional conformal radiation therapy for prostate cancer

PURPOSE

Radiation therapy for prostate cancer is associated with the development of post-treatment erectile dysfunction. Use of 3-dimensional (D) conformal delivery techniques has reduced delivery of radiation to periprostatic tissues. However, the exact magnitude of radiation that the corporeal bodies are exposed to using this delivery technique is currently unknown. This study was undertaken to calculate the radiation dose delivered to the corporeal bodies during 3-D conformal radiotherapy.

MATERIALS AND METHODS

Ten patients with proven prostate adenocarcinoma who underwent pre-therapy computerized tomography simulation and radiation delivery planning had the proximal corporeal bodies outlined on axial computerized tomography. The dose to the proximal penile tissues was then calculated using computer modeling.

RESULTS

The total dose of radiation administered to the prostate and seminal vesicles was 73.8 Gy. Mean radiation delivered to the most proximal 2 cm. of the corporeal bodies was 31 +/- 12.8 Gy., equating to 43% of the total dose of radiation delivered to the prostate and seminal vesicles.

CONCLUSIONS

These data indicate that large doses of radiation are being delivered to erectile tissue in the proximal penis despite careful pretreatment planning for 3-D conformal radiation therapy for prostate cancer. These data should encourage the development of radiation delivery strategies that minimize corporeal tissue exposure.

The extent of biopsy involvement as an independent predictor of extraprostatic extension and surgical margin status in low risk prostate cancer: implications for treatment selection

PURPOSE

We identify predictors of extraprostatic extension and positive surgical margins in patients with low risk prostate cancer (prostate specific antigen [PSA] 10 ng./ml. or less, biopsy Gleason score 7 or less and clinical stage T1c-2b).

MATERIALS AND METHODS

From August 1997 to January 1999, 143 previously untreated patients underwent radical retropubic prostatectomy for clinically localized prostate cancer. A total of 62 patients were low risk, with PSA 10 ng./ml. or less, biopsy Gleason score 7 or less and clinical stage T1c-2b, and had sextant biopsy with separate pathological evaluation of each sextant cores. PSA, clinical stage, biopsy Gleason score, average percentage of cancer in the entire biopsy specimen, maximum percentage of cancer on the most involved core, number of cores involved and bilaterality were evaluated for association with extraprostatic extension, seminal vesicle involvement and positive surgical margins.

RESULTS

Of the 62 patients 13 (21%) had extraprostatic extension, 6 (10%) seminal vesicle involvement and 20 (32%) positive surgical margins. Average percentage greater than 10% and maximum percentage greater than 25% were associated with extraprostatic extension (p = 0.01 and 0.004, respectively). Average percentage greater than 10%, maximum percentage greater than 25%, more than 2 cores involved and bilaterality were associated with positive surgical margins (p = 0.007, 0.01, 0.002 and 0.03, respectively). On multivariate analysis maximum percentage remained the only independent predictor of extraprostatic extension (p = 0.03), and the number of cores involved remained an independent predictor of positive surgical margins (p = 0.01). Biopsy Gleason score, PSA and clinical stage did not correlate with extraprostatic extension or positive surgical margins in this patient population.

CONCLUSIONS

In low risk prostate cancer the extent of biopsy involvement significantly correlates with the risk of extraprostatic extension and positive surgical margins. Biopsy information should be considered when selecting and modifying treatment modalities.

Inhibition of radiation-induced apoptosis by dexamethasone in cervical carcinoma cell lines depends upon increased HPV E6/E7

Through a glucocorticoid-responsive promoter, glucocorticoids can regulate the transcription of the human papillomavirus (HPV) E6 and E7 viral genes which target the tumour suppressor proteins p53 and Rb respectively. In C4-1 cells, the glucocorticoid dexamethasone up-regulated HPV E6/E7 mRNA and decreased radiation-induced apoptosis. In contrast, dexamethasone had no effect on apoptosis of cells that either lack the HPV genome (C33-a) or in which HPV E6/E7 transcription is repressed by dexamethasone (SW756). Irradiated C4-1 cells showed increased p53 expression, while dexamethasone treatment prior to irradiation decreased p53 protein expression. In addition, p21 mRNA was regulated by irradiation and dexamethasone in accordance with the observed changes in p53. Overall, glucocorticoids decreased radiation-induced apoptosis in cervical carcinoma cells which exhibit increased HPV E6/E7 transcription and decreased p53 expression. Therefore, in HPV-infected cervical epithelial cells, p53-dependent apoptosis appears to depend upon the levels of HPV E6/E7 mRNA.

RU486 increases radiosensitivity and restores apoptosis through modulation of HPV E6/E7 in dexamethasone-treated cervical carcinoma cells

OBJECTIVE

Cervical carcinoma tumors containing radioresistant cells are associated with decreased local control and survival. Therefore, strategies to increase cell kill during radiotherapy have a clear rationale. It was previously determined that treatment with the corticosteroid dexamethasone increased radioresistance and decreased apoptosis in C4-1 cervical carcinoma cells. The goal of this study was to determine whether hormone antagonists, specifically Mifepristone (RU486), could reverse the effects of dexamethasone on clonogenic survival and apoptosis following gamma-irradiation.

METHODS

Cervical carcinoma cell line C4-1 cells were exposed to 1 microM dexamethasone in the presence or absence of 1 microM Mifepristone (RU486), a hormone antagonist, and irradiation. Cells were analyzed for steroid-dependent HPV E6/E7 mRNA expression (by Northern blot analysis), clonogenic survival, and apoptosis (by Annexin V staining and the DNA fragmentation assay). In addition, p53 protein levels were determined by Western blot analysis.

RESULTS

The hormone antagonist RU486 reversed dexamethasone-dependent upregulation of E6/E7 mRNA and restored radiation-induced p53 expression, apoptosis, and clonogenic survival to levels similar to those observed following irradiation alone.

CONCLUSION

RU486 reverses glucocorticoid-dependent upregulation of HPV E6/E7, which corresponds to restoration of p53 expression, and restores radiosensitivity and apoptosis following gamma-irradiation. Therefore, it appears that along with radiation, RU486 may be a beneficial agent in the treatment of hormone-reactive cervical tumors.

Effect of tumor bulk on local control and survival of patients with T1 glottic cancer

PURPOSE

To evaluate the effect of tumor bulk in relation to various tumor-related prognostic factors and treatment-related variables on local control and survival of patients with T1 N0 M0 squamous cell carcinoma of the glottis.

MATERIALS AND METHODS

In 114 patients with T1 squamous cell carcinoma of the glottic larynx who were irradiated with curative intent, we determined the effect of tumor bulk in relation to mucosal extent (stage and anterior commissure involvement), histologic differentiation and various radiation factors, especially overall treatment time on local control and survival. Tumors were classified retrospectively as small surface lesions or bulky tumors. Seventy-seven patients had small lesions and 37 had bulky tumors. The anterior commissure was involved with cancer in 43 patients. The overall duration of irradiation ranged from 39 to 64 days. The median follow-up time was 6 years (range 5-24 years).

RESULTS

The 5-year actuarial local control rate for all patients was 82% after radiotherapy and 92% after salvage laryngectomy. On univariate analysis, bulky tumors and tumors involving the anterior commissure showed an adverse effect on local control, whereas the overall duration of irradiation had a borderline significance. The actuarial local control rate was 91% for small tumors and 58% for bulky tumors (P = 0.0002), 88% when the anterior commissure was not involved and 67% when the anterior commissure was involved (P = 0.01) and 89% when radiation was given in less than 50 days and 73% when irradiation exceeded 50 days (P = 0.06). On multivariate analysis. tumor bulk was the only significant factor that affected local control (P = 0.02). The 5-year actuarial survival for all patients was 73% and the disease-free survival was 92%.

CONCLUSION

This study shows that tumor bulk has a highly significant effect on the radiation control of T1 glottic cancer. Patients who had bulky tumors had lower local control and disease-free survival rates than those patients who had small tumors.

5-fluorouracil and folinic acid-induced mucositis: no effect of oral glutamine supplementation

In some clinical situations the endogenous production of glutamine may be insufficient to maintain optimal tissue structure and function such that glutamine becomes a conditionally essential amino acid. Studies in laboratory animals have demonstrated that glutamine supplementation can reduce the incidence and severity of cytotoxic-induced mucositis. This study examined the role of oral glutamine supplementation in the management of mucositis caused by 5-fluorouracil (5-FU) and folinic acid. Twenty-eight patients with gastrointestinal cancers were randomised to receive 16 g of glutamine per day for 8 days, or placebo, in a randomised double-blind trial before crossing over to the alternative supplement during the second treatment cycle. The supplement was well tolerated with no apparent adverse effects, but failed to have any significant effect on oral mucositis assessed by the patients or investigator. The possible reasons for this apparent lack of benefit are discussed.