Factors influencing late rectal toxicity after radiotherapy of localized prostate cancer
Bibliographic record
Abstract
4730 Background: Radiation injury to the rectum is a common sequelae of radiotherapy to the prostate because of the proximity of the rectal wall to the prostate. The objective of this article will be to review the experience at this institution and identify factors influencing late rectal toxicity after radiotherapy for localized prostate cancer. Methods: The cohort consists of 426 patients with localized prostate cancer treated with conformal radiotherapy from September 2000 to March 2003. RTOG scales were used to evaluate late rectal morbidity and a modified CTC/RTOG scale was used to grade late rectal bleeding at each follow up visit. Patients were assessed 6 - 8 weeks after radiation, and then every 6 months. The endpoints of interest included: rectal toxicity grades 2–4, any late rectal bleeding, and late rectal bleeding grades 2–4. Patient and treatment factors were analyzed. Results: The median ICRU prostate dose was 73.7 Gy (range 50–82 Gy). Pelvic lymph node irradiation was given in 15% of patients. Neoadjuvant hormones were given in 80% of patients. Median follow-up of the patients was 17.5 months. No patient developed grade 4 toxicity. The 18 month Kaplan-Meier rates of late rectal bleeding grade 2–3, any rectal bleeding, and ano-rectal toxicity grade 2–3 was 8.5%, 24.9%, and 17.1%. Univariate analysis of patient factors including age, cardiovascular disease, diabetes, hypertension, and weight did not show any influence on rates of late rectal bleeding. However, treatment factors including the percent rectum receiving greater than 60Gy and 70Gy and the total prostate dose were significant in increasing grade 2–3 ano-rectal toxicity. The percent rectum receiving greater than 70Gy and total prostate dose were significant in increasing grades 1–3 rectal bleeds. Conclusions: The volume of rectum receiving greater than 60Gy and 70Gy is significant in influencing rates of late rectal toxicity and should be minimized. Rectal bleeds and ano-rectal toxicity are also affected by the total prostate dose and should be monitored carefully in dose escalation trials. No significant financial relationships to disclose.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".