Breast cancer risk and breast screening for trans people: an integration of 3 systematic reviews

Olivia Meggetto; Leslea Peirson; Mafo Yakubu; Mufiza Farid-Kapadia; Michelle Costa-Fagbemi; Shamara Baidoobonso; Jessica Moffatt; Lauren Chun; Anna M Chiarelli; Derek Muradali

doi:10.9778/cmajo.20180028

Breast cancer risk and breast screening for trans people: an integration of 3 systematic reviews

CMAJ Open. 2019 Oct 1;7(3):E598-E609. doi: 10.9778/cmajo.20180028. Print 2019 Jul-Sep.

Affiliations

¹ Prevention and Cancer Control (Meggetto, Peirson, Yakubu, Farid-Kapadia, Costa-Fagbemi, Baidoobonso, Moffatt, Chun, Chiarelli, Muradali), Cancer Care Ontario; Dalla Lana School of Public Health (Chiarelli), University of Toronto; Department of Medical Imaging (Muradali), St. Michael's Hospital; Department of Medical Imaging (Muradali), University of Toronto, Toronto, Ont. olivia.meggetto@cancercare.on.ca.
² Prevention and Cancer Control (Meggetto, Peirson, Yakubu, Farid-Kapadia, Costa-Fagbemi, Baidoobonso, Moffatt, Chun, Chiarelli, Muradali), Cancer Care Ontario; Dalla Lana School of Public Health (Chiarelli), University of Toronto; Department of Medical Imaging (Muradali), St. Michael's Hospital; Department of Medical Imaging (Muradali), University of Toronto, Toronto, Ont.

Abstract

Background: Trans people face uncertain risk for breast cancer and barriers to accessing breast screening. Our objectives were to identify and synthesize primary research evidence on the effect of cross-sex hormones (CSHs) on breast cancer risk, prognosis and mortality among trans people, the benefits and harms of breast screening in this population, and existing clinical practice recommendations on breast screening for trans people.

Methods: We conducted 2 systematic reviews of primary research, 1 on the effect of CSHs on breast cancer risk, prognosis and mortality, and the other on the benefits and harms of breast screening, and a third systematic review of guidelines on existing screening recommendations for trans people. We searched PubMed, MEDLINE, Embase, CINAHL, the Cochrane Database of Systematic Reviews and grey literature sources for primary research, guidelines and position statements published in English between 1997 and 2017. Citations were screened by 2 independent reviewers. One reviewer extracted data and assessed methodological quality of included articles; a second reviewer verified these in full. The results were synthesized narratively.

Results: Four observational studies, 6 guidelines and 5 position statements were included. Observational evidence of very low certainty did not show an effect of CSHs on breast cancer risk in trans men or trans women. Among trans women, painfulness of mammography and ultrasonography was low. There was no evidence on the effect of CSHs on breast cancer prognosis and mortality, or on benefits and other harms of screening. Existing clinical practice documents recommended screening for distinct trans subpopulations; however, recommendations varied.

Interpretation: The limited evidence does not show an effect of CSHs on breast cancer risk. Although there is insufficient evidence to determine the potential benefits and harms of breast screening, existing clinical practice documents generally recommend screening for trans people; further large-scale prospective comparative research is needed.