Metachronous colon cancer risk following surgery for first primary rectal cancer in Lynch syndrome
Bibliographic record
Abstract
It is known that metachronous colorectal cancer risk for Lynch syndrome patients with primary colon cancer is high and total colectomy is the preferred option [ 1 ]. However if the index primary cancer is in the rectum, management advice is complicated by considerations of worsening bowel function or stoma formation. To aid surgical decision-making, we estimated the risk of metachronous colon cancer for Lynch syndrome patients who underwent either anterior resection or abdominoperineal resection for primary rectal cancer. This retrospective cohort study comprised 79 MMR gene mutation carriers (18 MLH1 , 55 MSH2 , 4 MSH6 and 2 PMS2 ) from the Colon Cancer Family Registry who had a surgical resection for their first primary rectal cancer. Age-dependent cumulative risks of metachronous colon cancer were calculated using the Kaplan-Meier method. Risk factors for metachronous colon cancer were assessed using a Cox proportional hazards regression. During 866 person-years of observation (median 9 years; range 1-32 years) since diagnosis of first rectal cancer, a total of 21 (27%) carriers were diagnosed with metachronous colon cancer (incidence 24.2; 95% CI 15.8–37.2 per 1000 person-years). Incidence for carriers who had an anterior resection (26.8; 95% CI 15.5–46.1 per 1000 person-years) was not different from that for carriers who had an abdominoperineal resection (21.0; 95% CI 10.5–42.1 per 1000 person-years) ( P =0.1). Cumulative risk of metachronous colon cancer was 19% (95% CI 9–31%) at 10 years, 47% (95% CI 31–68%) at 20 years and 69% (95% CI 45–89%) at 30 years after surgical resection. There was no difference in the frequency of surveillance colonoscopy between two types of surgery (one colonoscopy per 1.1 (95% CI 0.9–1.2) years after anterior resection vs. one colonoscopy per 1.4 (95% CI 1.0–1.8) years after abdominoperineal resection). For carriers of MMR gene mutations who contract rectal cancer, the metachronous cancer risk is substantial and mirrors that seen for carriers undergoing segmental resection for primary colon cancer [ 1 ], despite the majority continuing to receive frequent surveillance colonoscopy. This risk needs to be considered when the extent of surgery for primary rectal cancer is planned. Whereas total colectomy for primary colon cancer in mutation carriers is appropriate, for primary rectal cases this strategy has major implications for continence and need for stoma. Nevertheless, given the high metachronous risk, this needs serious consideration especially for younger patients.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.006 | 0.009 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| 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 teacher head, 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".