Effect of very small tumor size on recurrence-free survival and breast cancer-specific mortality stratified by guideline adherence: An analysis of the BRENDA Study Group.

Abstract

1096 Background: Small tumor size (<5mm, T1a) carry an excellent prognosis, despite a variety of treatment approaches. Controversy exists over the extent of treatment, as to whether less than conventional treatment can be done. We therefore sought to explore the effect of very small tumor size on RFS and BCSM stratified by guideline adherence. Methods: The multicenter study population included 8935 early breast cancer patients diagnosed between 1992-2008, where 614 patients (6.9%) were T1a. T1a-patients were categorized according to guideline adherence and the influence on survival was calculated by Cox proportional hazard analyses (adjusted for age, grading, nodal status, hormonal status and co-existing morbidity). Results: The median age was 61 years and the median follow-up was 55 months. 449 [73.1%] patients were postmenopausal. 13.1% had G1, 61.9% G2 and 25% G3. 81.9% were HR positive and 18.4% HER2/neu-positive. 77.1% were N0, 11.9% had 1-3 and 11% more than 3 affected lymph nodes. Only 262 (42.7%) pts. were guideline adherent. Compared to guideline adherent patients RFS and BCSM were significantly (p< 0.001) worse for guideline-non-adherent patients (RFS: HR=3.88; 95% C.I.: 1.91-7.87) and (BCSM: HR= 4.28; 95% C.I.:2.04-9.00). After adjusting for age, grading, nodal status, hormone receptor status and comorbidity guideline adherence was still the most important variable for RFS and BCSM (RFS: p<0.001; HR=3.71; 95%C.I.: 1.80-7.67) and (BCSM: p<0.001; HR=3.82; 95% C.I.:1.80-8.11).The most important impact on RFS and BCSM had guideline violations of radiation (RFS: p=0.001; HR=3.19;95%C.I.:1.66-6.13) and (BCSM: p=0.009;HR=2.42;95%C.I.:124-4.72) respectively of chemotherapy (RFS: p=0.001;HR=1.43; 95%C.I.:1.43-4.39) and (BCSM: p<0.001;HR=3.17;95%C.I.:1.84-5.46). Conclusions: There is a strong association between guideline adherence and improved recurrence free survival and reduced breast cancer-specific mortality for breast cancer patients with very small tumor size. Violation of treatment guidelines for postoperative irradiation or chemotherapy is clearly associated with a deterioration of prognosis.