Novel hereditary breast cancer gene mutations: Should there be greater concern regarding ovarian cancer risk?

Abstract

INTRODUCTION:

As the use of multi-gene breast cancer panel testing increases the phenotype of the included genes continues to evolve. PALB2 and NBN have a well characterized association with breast cancer and are included on many breast cancer gene panels. Germline PALB2 and NBN mutations have been identified in a small percentage of ovarian carcinoma cases with one study reporting a non-significant twofold increase in carriers of the PALB2 mutations amongst ovarian cancer patients (P= 0.4). Similar to BRCA1 and BRCA2 both genes are members of the Fanconi Anemia pathway therefore a potential increased risk for both breast and ovarian cancer could be anticipated. However at present overall the current literature on the association with ovarian cancer is sparse. Here we present the cases of three hereditary breast and ovarian cancer families found to carry pathogenic mutations within the PALB2 and NBN genes. In all three families the proband was diagnosed with ovarian or fallopian tube cancer and carries a pathogenic PALB2 or NBN mutation. Our PALB2 family carries the well-known French Canadian founder mutation, c.2323C>T, and includes the proband who was diagnosed with a stage II-C, grade 3, fallopian tube carcinoma at age 58, her heterozygote sister with ovary cancer at 68 and her mother with ovary cancer at 43 who was not able to be tested. This PALB2 proband has 5 sisters, 7 brothers and 41 nieces and nephews with only one sister diagnosed with breast cancer at 69 who also is PALB2 positive and a maternal grandmother with breast cancer at 48 who was unable to be tested. The NBN Slavic founder mutation, c.657_661del, was discovered in a 66 year old woman with stage IV, high-grade serous ovarian cancer having a mother with breast cancer at 91 and a maternal aunt with ovary cancer at 59 who have not yet been tested. Lastly, our patient from Laos with a diagnosis of a stage II-C endometrioid adenocarcinoma of the ovary diagnosed at 38 years old was found to carry the deleterious NBN mutation, c.1550dupA. She is not aware of any cancer family history and reports a large family including five brothers, four sisters and multiple aunts and uncles on both side of the family.

CONCLUSION:

These case studies suggest a link between PALB2 and NBN, two known breast cancer susceptibility genes, and hereditary ovarian cancer risk. These observations suggest that further data are needed to accurately evaluate ovarian cancer risk within novel hereditary breast cancer genes now commonly tested as part of multiplex panel analysis.