Breast Biopsy During Post-treatment Surveillance of Screen-Detected Breast Cancer Patients Yields High Rates of Benign Findings.

BACKGROUND

The incidence of breast biopsy following treatment for breast cancer is not well-characterized. We sought to determine the frequency and outcomes of breast biopsy and the need for subsequent surgery in patients treated with breast-conserving surgery (BCS).

METHODS

Using a prospective database, we identified patients in Alberta, Canada, treated with BCS for screen-detected breast cancer or ductal carcinoma in situ (DCIS) from 2010 to 2014. Post-treatment breast procedures were identified from physician claims data. Multivariable analysis was performed to identify factors associated with biopsy.

RESULTS

We included 2065 patients with a median of 6.4 years of follow-up; most had DCIS (n = 426, 20.6%) or stage I disease (n = 1385, 67.1%). Post-treatment core biopsy was performed in 389 (18.8%, 95% confidence interval [CI] 17.2-20.6%) patients, and excisional biopsy was performed in 19 (0.9%, 95% CI 0.6-1.4%) patients. The per-patient benign-to-malignant biopsy ratio was 3.2 to 1, and the overall malignancy rate was 6.1% (95% CI 5.1-7.2%). Younger age, proximity to a cancer center, positive margins, and the use of magnetic resonance imaging were associated with biopsy (p < 0.05). Additional surgery was performed in 150 (7.3%, 95% CI 6.2-8.5%) patients; 93 (4.5%, 95% CI 3.6-5.4%) patients underwent mastectomy. Surgery was performed for local recurrence/ipsilateral cancer in 62 (3.0%) patients, contralateral breast cancer in 60 (2.9%) patients, bilateral breast cancer in 3 (0.1%) patients, and benign indications/prophylaxis in 25 (1.2%) patients.

CONCLUSIONS

One in five patients required breast biopsy during post-treatment surveillance following BCS and most revealed benign findings. Rates of additional surgery, especially subsequent mastectomy due to ipsilateral or contralateral malignancy, were low. Patients can be reassured of these findings during pre-treatment counseling and post-treatment surveillance.