Dose/Volume Relationship of Late Rectal Bleeding After External Beam Radiotherapy for Localized Prostate Cancer

Abstract

To date, five patients have had grade 1 late rectal toxicity (one CRT case and four SCIM-RT cases), one patient had grade 2 late rectal toxicity (CRT), and three patients had grade 3 late rectal toxicity (all CRT cases). Because of the low number of events, the analysis was performed with all patients experiencing rectal bleeding grouped together. The actuarial rectal bleeding rates at 18 and 24 months were 6% and 8%, respectively. The actuarial rectal bleeding rates at 24 months were identical (8%) for both SCIM-RT and CRT. A multivariate analysis of the following parameters was performed to determine independent predictors of rectal bleeding: age (continuous variable), race (Caucasian vs African American), coverage of seminal vesicles (yes vs no), adjuvant androgen deprivation (yes vs no), technique (CRT vs SCIM-RT), Radiation Therapy Oncology Group acute rectal toxicity score (continuous variable), VrPr (continuous variable in cubic centimeters), and %VrPr (continuous variable). Only the VrPr (cubic centimeter) was an independent predictor of rectal bleeding; %VrPr was not. With different cut-off levels being used, a VrPr of 15 cm3 was significant on univariate analysis; the actuarial rectal bleeding rates at 24 months for patients with a VrPr < or = 15 cm3 versus a VrPr > 15 cm3 were 5% versus 22%, respectively. CONCLUSION> In our study sample, which included both conformal and intensity-modulated radiotherapy patients, the volume of rectum receiving the prescribed radiation dose (the equivalent of 78 Gy) was an independent predictor of late rectal bleeding. The percent of rectal volume receivingthe full dose was not. Using actual volume rather than percent volume also avoids the dependence on the extent of rectal volume contours. We recommend 15 cm3 as the cut-off of the rectal volume not to exceed the prescription dose. The rectal bleeding rate at 2 years for cases with < 15 cm3 receiving the full dose was only 5%.

Dose variation during hypofractionated image-guided radiotherapy for prostate cancer: Planned versus delivered

“…This interpretation was based on the planning data and the recommendation that not more than 15 cc of the planned rectal volume should receive the prescribed dose. [17] In our study, the above planning constraint was met in all the patients and only six of the 187 (3.2%) treatment fractions analysed had a rectal volume of >15cc (and all less than 17cc) receiving the prescribed dose. This is an encouraging finding and may be attributed to the daily soft tissue image guidance used.…”

The prognostic impact of cytokeratin‐positive cells in bone marrow of patients with localized prostate cancer

“…28,29 However, as shown by Kupelian et al, rising PSA after curatively intended local treatment in general predicts the development of clinical progression, often after long intervals. 30 Pound et al reported that PSA progression preceded the diagnosis of distant metastases by a median time of 8 years after radical prostatectomy. 31 ASTRO has published guidelines for identification of patients with biochemical failure after definitive radiotherapy.…”

The Lessons of QUANTEC: Recommendations for Reporting and Gathering Data on Dose–Volume Dependencies of Treatment Outcome

“…Preferably, data used for NTCP analyses should include the full organ volume (see reference (19): page 107, paragraph 2). When this is not possible, either a standard method of normalization, or absolute volumes should be used (see reference (21): page 63 Methods and Materials paragraph 2, and table 1). A clear statement of the definition of the organ volume should be given, paying close attention to such issues as length of linear structures included (e.g.…”