A Case-Case Comparison of Molecular Subtype for Breast Cancer, Younger and Older Age at Diagnosis, in Puerto Rico, 2010-2019

• Published in: JCO global oncology Vol. 10; no. Supplement_1; pp. 8 - 9
• Main Authors: Velazquez, Eugenia Torres, Rosario-Rosado, Rosa V., García-Berdecía, Rafael, Climent, Consuelo, Freudenheim, Jo L.
• Format: Journal Article
• Language: English
• Published: 01.07.2024
• ISSN: 2687-8941; 2687-8941
• DOI: 10.1200/GO-24-12000

PURPOSE Breast cancer (BC) accounted for 28.9% of cancer cases and 18.9% of cancer deaths, an average of 437 deaths per year, among women in Puerto Rico (PR) between 2014 and 2018. Prognosis differs by molecular subtype; little is known about the distribution of these subtypes in the population in PR and whether there are differences in distribution by age. We described the distribution of breast cancer molecular subtypes and compared them for younger and older age at diagnosis among women in PR. METHODS This case-case study used data from the PR Central Cancer Registry (PRCCR). Included were women aged ≥21 with primary invasive BC, and information available on estrogen (ER) and progesterone receptor (PR) and HER2 status, with diagnosis between January 1, 2010 and December 31, 2019. Those with either ER+ or PR+ were classified as HR+, those with both ER- and PR- as HR-. BC subtypes were classified as: HR+/HER2-, HR+/HER2+, HR-/HER2-, and HR-/HER2+. Five categories of age were examined: ≤39, 40-49, 50-59, 60-69 and ≥70 years. We compared the distribution of BC subtypes by age at diagnosis with polytomous logistic regression, utilizing HR+/HER2- subtype and the ≤39 age cases as the reference, adjusting for year of diagnosis and tumor stage. RESULTS Among 13,525 eligible cases, there were 674 aged ≥39 [5.0%], 1,988 aged 40-49 [14.7%], 3,108 aged 50-59 [23.0%], 3,884 aged 60-69 [28.7], and 3,871 aged ≥70 [28.6%]). Of the total, 9,634 (71.2%) cases were HR+/HER2-, 1,761 (13.0%) were HR-/HER2-, 1,456 (10.8%) were HR+/HER2+, and 674 (5.0%) were HR-/HER2+. Compared to cases ≤39, cases ≥70 years were less likely to have HR+/HER2+ tumors (adjusted OR: 0.31; 95% CI: 0.25, 0.40), HR-/HER2- (adjusted OR: 0.45;95% CI: 0.36, 0.56) and HER2-enriched (adjusted OR: 0.40;95% CI: 0.28, 0.57). CONCLUSION In this population-based study of women in PR, younger women had a higher likelihood of more aggressive BC molecular subtypes as compared to their older counterparts.