Abstract PS1-07: Elderly breast cancer patients benefit from surgery according to guidelines
Authors: Mejdahl Mathias Kvist , Christensen Mette Haulund , Nielsen Birgitte Paaschburg , Tvedskov Tove HolstFiltenborg 
Published: February 2021

Abstract
Background: With a globally increasing population of otherwise healthy people above 70 years, more knowledge on treatment and prognosis of breast cancer patients in this group is needed. In Denmark, the Danish Breast Cancer Group describes national treatment guidelines for diagnostic work-up and surgical and oncological treatment of all patients with primary invasive breast cancer with no upper age limit. Still, many patients ≥70 years, regardless of comorbidity, do not adhere to treatment guidelines, often receiving less imaging and less treatment than recommended. The aims of the present study were to examine, among patients ≥70 years with primary invasive breast cancer, whether endocrine treatment only, resulted in an inferior breast cancer related survival compared to standard surgical and oncological treatment, to examine whether patients treated with breast conserving surgery (BCS) with no preoperative imaging had a higher risk of local recurrence than patients receiving preoperative imaging, and finally to examine whether clinically node negative patients had a higher risk of regional recurrence if they did not receive axillary staging. Methods: All women, ≥70 years, diagnosed with primary invasive breast cancer and treated at the Department of Breast Surgery at Herlev Hospital, Denmark, from 2000-2007 were included. Patients were prospectively registered in a hospital-based database. Differences in standardized mortality ratios (SMR) between patients treated by surgery, endocrine therapy only, or endocrine therapy followed by surgery were estimated by Poisson regression and evaluated by rate ratios. Differences in local recurrence between patients with and without preoperative imaging before BCS, and in regional recurrence between surgically treated patients with and without a sentinel lymph node biopsy, with axillary clearance in case of a positive sentinel node, excluding clinically node positive patients directly treated with an axillary clearance, were estimated by Cause Specific Hazards Models and evaluated by cause specific hazard ratios (HR). Adjustments were made for age, comorbidity, adjuvant radiotherapy, tumor size, time since diagnosis, and time period. Results: In total 1,142 patients were included in the study. The median age was 77 years. For overall mortality, median follow-up was 7.80 years, with 795 (69.6%) dying during follow-up, and for recurrence 6.25 years. 52 were registered with local recurrence and 39 with regional recurrence. Patients who received only endocrine therapy had a significantly higher SMR than patients treated with primary surgery (adj. RR=2.57; 95% CI: 2.01-3.30), while patients who received endocrine therapy followed by later surgery did not (RR=1.23; 95% CI: 0.91-1.66). 253 out of 580 patients with BCS (43.6%) did not have preoperative imaging. Patients without imaging did not have a higher risk of local recurrence compared to patients with preoperative imaging (adj. HR=1.14; 95% CI: 0.36-3.67). 13 out of 197 surgically treated patients without axillary surgery (6,8%) had regional recurrence, while only 7 out of 428 patients (1.6%) with axillary staging by sentinel node biopsy had regional recurrence. This difference was significant (adj. HR 4.68 95% CI=1.53-14.37).
Conclusions: In the present study we have shown that women ≥70 years, diagnosed with primary invasive breast cancer, have a higher mortality if they are not surgically treated, and they have a higher risk of regional recurrence if they are not offered axillary staging. The study emphasizes that unless elderly patients have comorbidity contraindicating surgery, they should be treated according to guidelines.
Citation Format: Mathias Kvist Mejdahl, Mette Haulund Christensen, Birgitte Paaschburg Nielsen, Tove HolstFiltenborg Tvedskov. Elderly breast cancer patients benefit from surgery according to guidelines [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS1-07.