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Jun 27, 2020 12:24PM
Jun 27, 2020 12:24PM
Togethertolearn, I agree with your logic when it comes to a lumpectomy. Unfortunately the same approach usually can't be applied to those who've had a mastectomy, since all the breast tissue has been removed so there is nothing further (except chest muscle) that can be removed surgically to achieve wider margins.
MinusTwo, the issue after a MX for DCIS is that there isn't agreement as to what is an acceptable margin. Emily indicated that her chest wall margin was 1mm. By some definitions that is an acceptable margin, by other definitions it is not. Certainly no one would say that 1mm is a generous margin. To complicate matters, age and grade may come into play as well.
The following study, the first I recall reading years ago about DCIS margins after a MX, suggests a significantly higher recurrence rate for those with margins of less than or equal to 2mm, but within this study, the higher risk seems to only apply to those who were under age 60 and had grade 3 DCIS. That said, I don't know the age and grade distribution within the study, which only included 80 patients.
"With a median follow-up of 61 months, 6 (7.5%) of the 80 patients developed local recurrence. Of the 31 patients with a margin of less than or equal to 2 mm, 5 (16%) developed local recurrence vs. only 1 (2%) of 49 patients with a margin of 2.1–10 mm (p = 0.0356). Of the 6 patients with local recurrence, 5 had high-grade disease and/or comedonecrosis. All six recurrences were noted in patients <60 years old."
This more recent, much larger study found some small differences but nothing statistically significant and therefore came to a different conclusion:
Some key points from the study findings: "After mean follow-up of 10.2 years, 36 patients (2.4%) developed chest wall recurrence (17 were DCIS, 19 were invasive cancer)....
...We examined the features of women who developed chest wall recurrence in an effort to identify factors associated with an increased risk of chest wall recurrence following mastectomy for pure DCIS. Individuals who developed chest wall recurrence were more likely to be younger than 45 years at diagnosis (19.4 vs. 16.2%; p = 0.20), have high nuclear grade DCIS (36.1 vs. 27.8%; p = 0.41), or close resection margins (52.8 vs. 43.6%; p = 0.23) but these differences did not achieve statistical significance....
...On univariate (and multivariable) analysis, none of the factors including resection margin width (univariate HR: ≤2 mm = 2.1 (95% CI 0.86–5.1), p = 0.10), age at diagnosis (age < 45 years, HR = 1.29 (95% CI 0.55–3.02); p = 0.72), high nuclear grade (univariate HR = 3.0 (95% CI 0.4–23.1), p = 0.29), subtype, presence of multifocality (univariate HR = 0.7 (95% CI 0.28–1.62), p = 0.36), presence of comedo necrosis (univariate HR = 1.7 (95% CI 0.23–13.1), p = 0.60) or breast surgeon volume (univariate HR for low volume = 2.6 (95% CI 0.89–7.37), p = 0.08) were associated with an increased risk of chest wall recurrence....
...Among 130 women <45 years at diagnosis with close (≤2 mm) margins, the 10 year rate of chest wall recurrence was <5%....
....Chest wall radiotherapy is associated with a risk of acute and late toxicity, including a detrimental effect on cosmesis following breast reconstruction. Therefore, we aimed to identify baseline factors associated with the development of isolated chest wall recurrence in women with pure DCIS treated by mastectomy, in an effort to identify the subset of individuals who might benefit from post-mastectomy adjuvant radiotherapy. We did not identify any feature, alone or in combination, that was associated with a significant increased risk of chest wall recurrence (at 10 years of follow-up) such that routine radiotherapy should be recommended."
“No power so effectually robs the mind of all its powers of acting and reasoning as fear.” Edmund Burke