Breast cancer after reduction mammoplasty: A population-based analysis of incidence, treatment, and screening patterns.
Bibliographic record
Abstract
e18785 Background: The incidence of breast cancer after reduction mammoplasty has been demonstrated to be lower than the general population in several large registry trials performed in primarily European populations; North American data is lacking. Tissue rearrangement during reduction mammoplasty may lead to abnormal breast imaging results postoperatively resulting in more challenging screening.The purpose of this study was to describe the incidence and treatment of breast cancer after reduction mammoplasty in a more contemporary Canadian population, and to better understand the use of breast cancer screening modalities in these patients. Methods: This population-based retrospective analysis utilized the Discharge Abstract Database held by the Canadian Institute for Health Information (CIHI) and the National Ambulatory Care Reporting System (NACRS) to identify all women 20 or older who underwent reduction mammoplasty in Alberta, Canada between 2003 and 2007. The incidence and treatment of breast cancer was compared among patients who underwent reduction mammoplasty and age-sex matched controls in Alberta. Imaging utilization post mammoplasty, including use of mammography, ultrasound and breast biopsy was also compared between these two groups. Results: A total of 8,021 patients over 20 years old underwent reduction mammoplasty during the study period. Patients were followed for an average of 12.6 years. Most women (6,417, 80%) underwent reduction mammoplasty surgery between the ages of 20-50. Compared to controls, women who underwent reduction mammoplasty had more comorbidities (Charlson Comorbidities > 1: 5.2% vs 4.2% controls, p < 0.0001). Overall, 89 (1.1%) patients who underwent reduction mammoplasty developed breast cancer after surgery, compared to 453 (1.9%) controls (p < 0.0001). Among patients diagnosed with breast cancer, there was no difference in patient characteristics, tumor size, histology and grade between the two groups. Fewer patients presented with metastatic disease after reduction mammoplasty (0% vs 5.1%, p = 0.043). The surgical treatment differed between groups; patients who underwent reduction mammoplasty were significantly more likely to undergo mastectomy for breast cancer (41.6% vs 1.5%, p < 0.0001). Women who underwent reduction were more likely to undergo mammography (66.7% vs 58.7%, p < 0.001), ultrasound (29.2% vs 26.2%, p < 0.0001) and biopsy for benign disease (7.2% vs 6%, p = 0.0001) compared to controls. Conclusions: Despite an increased frequency of breast cancer screening, the incidence of breast cancer is lower after reduction mammoplasty compared to women who did not undergo breast reduction. After a diagnosis of breast cancer, surgical treatment patterns differ between groups despite similarities in tumor characteristics, whereby mastectomy is more common in those who have undergone breast reduction.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.004 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".