Breast
Brittany L. Murphy, MD
Breast Surgical Oncologist
Banner MD Anderson
Glendale, Arizona, United States
Disclosure: Disclosure information not submitted.
Women with a history of breast cancer (BC) are more commonly diagnosed with other primary malignancies (OPM) compared to the general population. We sought to evaluate OPMs in patients with BC who underwent germline testing with a hereditary BC gene panel.
Methods:
We identified women ≥18 years with a history of unilateral BC who underwent multi-gene panel testing 1/2014-8/2019 at our institution. Patient, tumor, and treatment factors for BC and OPM diagnoses were collected for descriptive, univariate, and overall survival (OS) analyses.
Results:
Among 1163 eligible patients, 330 (28.4%) had an OPM. Median follow-up was 4.1 years and median age was 46 years at BC diagnosis. 209 (18%) patients had a BRCA 1 or 2 pathogenic variant (PV), 306 (26.4%) non-BRCA PV, and 648 (55.7%) had no germline mutation. Most common non-BRCA PVs were: CHEK2 (n=80, 26.1%), PALB2 (n=55, 18.0%), ATM (n=48, 15.7%), P53 (n=29, 9.5%), and other (n=94, 30.7%). Development of an OPM varied with germline testing result with 18.6% (39/209) of BRCA patients developing an OPM, 31.8% (204/648) with no germline mutation, and 28.4% (87/306) with a non-BRCA PV, p< 0.0001, Table 1.
The most common OPMs included ovarian (n=60), uterine (n=44), sarcoma (n=36), melanoma (n=27), colorectal (n=22), and lymphoma (n=20). Ovarian and uterine cancer were associated with germline mutation, p=0.001 and 0.003 respectively, with greatest diagnosis in patients with no germline mutation, followed by a BRCA PV for ovarian cancer, and a non-BRCA PV for uterine cancer.
The 5-year OS was 96%. Patients with an OPM had a shorter OS compared with those who did not develop an OPM at 5-years after BC diagnosis, 93.4% vs 97.5%, P=0.002. There was no difference between germline testing result and OS, P=0.3.
Conclusions: Over 25% of women with BC who underwent germline panel testing were diagnosed with OPM over short-term follow up, and the diagnosis of OPM was associated with reduced OS. These rates of OPMs are higher than the 6.6% rate reported for the general population of BC patients without germline testing. These data have implications in counseling BC patients who undergo germline testing regarding future cancer screening.