Postoperative Radiotherapy for Breast Cancer: Growing Evidence for an Impact on Survival
Bibliographic record
Abstract
Postoperative radiotherapy for breast cancer is known to substantially reduce the risk of locoregional recurrence, both when given after mastectomy and after breast-conserving surgery. Recent reports [cited below] suggest that radiotherapy following mastectomy may also have a beneficial impact on survival, and the article by Vinh-Hung et al. (1), published in this issue of the Journal, further suggests that radiotherapy given after breast-conserving surgery improves survival. Three randomized clinical trials (2–4) of postmastectomy radiotherapy, conducted in Canada and Denmark, have shown a 9%–10% improvement in overall survival at 10 years for patients that received radiotherapy compared with patients who did not receive radiotherapy. These results contrast with those of a patient-based meta-analysis of randomized clinical trials (5) in which radiotherapy was shown to be associated with a reduced risk of dying of breast cancer; however, this reduced risk was offset by increased mortality from vascular causes. There are several possible explanations for this apparent discrepancy. Many of the trials included in the patient-based meta-analysis (5) were initiated a long time ago, and these trials were often small and involved radiotherapy techniques and fractionation schedules that resulted in higher doses to the heart than are obtained with modern radiotherapy techniques. In a reanalysis of data from these trials, a substantial reduction was found in the risk of mortality associated with radiotherapy of 12.4% (P<.001) when only recent trials were included (6). In addition, patients treated in the Canadian and Danish trials (2–4) received adjuvant chemotherapy and/or tamoxifen (i.e., systemic therapy) in conjunction with radiotherapy. Hence, if the burden of distant micrometastases can be reduced by systemic therapy, then radiotherapy given to locoregional sites might prevent secondary dissemination, thus being potentially curative. This hypothesis is supported by the results of a meta-analysis of randomized clinical trials of adjuvant radiotherapy (7) in which patients also received systemic therapy. In these trials, adjuvant radiotherapy statistically significantly reduced the risk of mortality (odds ratio = 0.83, 95% confidence interval [CI] = 0.74 to 0.94; P = .04). These results have led to the general acceptance that radiotherapy given after mastectomy to patients at moderate or high risk of dying from breast cancer has favorable effects on survival.
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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 | 0.004 | 0.025 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.014 | 0.010 |
| Insufficient payload (model declined to judge) | 0.009 | 0.004 |
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".