Examining the common aetiology of serous ovarian cancers and basal-like breast cancers using double primaries.
BACKGROUND
The somatic molecular profiles of basal-like breast cancers and high-grade serous ovarian cancers share many similarities, leading to the hypothesis that they have similar aetiologies, in which case they should occur together in the same patient more often than expected.


METHODS
We identified 545 women with double independent primary cancers of the breast and ovary reported to the California Cancer Registry from 1999 to 2013 and examined the coincidence of subtype combinations.


RESULTS
For most subtype combinations the observed frequencies were similar to their expected frequencies, but in 103 observed cases vs 43.8 expected (O/E=2.35; 95% CI 1.90-2.81) a triple-negative breast tumour (typically basal-like) was matched with a serous ovarian tumour (typically high-grade).


CONCLUSIONS
The results provide compelling evidence that basal-like breast cancer and high-grade serous ovarian cancer share a much more similar aetiology than breast and ovarian cancers more broadly. Further research is needed to clarify the influence of germ-line BRCA1 mutations and other risk factors on these results.
Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY 10017, USA.
Colin B
CB
Begg
Massachusetts General Hospital and Harvard Medical School, Boston, MA 02115, USA.
Megan S
MS
Rice
Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY 10017, USA.
Emily C
EC
Zabor
Brigham and Women's Hospital, Harvard Medical School and Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA.
Shelley S
SS
Tworoger
D001943:Breast Neoplasms / Q000150:complications* / Q000473:pathology; D002280:Basal Cell Carcinoma / Q000209:etiology* / Q000473:pathology; D018284:Cystadenocarcinoma, Serous / Q000209:etiology* / Q000473:pathology; D005260:Female; D006801:Humans; D009367:Neoplasm Staging; D009378:Neoplasms, Multiple Primary / Q000209:etiology* / Q000473:pathology; D010051:Ovarian Neoplasms / Q000150:complications* / Q000473:pathology; D011379:Prognosis