Breast cancer

‘Precision prevention’ effort required in breast cancer after study shows underuse of tamoxifen

Australian women at elevated risk of breast cancer are under-utilising available risk-reducing medications (RRMed) such as tamoxifen and anastrozole.

A study of 2,895 Australian women enrolled in the Kathleen Cuningham Foundation Consortium for Research into Familial Breast Cancer cohort (kConFab) between 1997 and 2008 and eligible for RRMed found only 2.4% had ever taken one of the agents.

“Use may be even lower for women at increased breast cancer risk in the general Australian population, given our participants likely had greater exposure to information about RRMed due to their enrolment in a familial cohort study. Despite the low use of RRMed in a cohort,” the investigators said.

The study, published in The Breast, said RRMed was recommended for women at moderate risk of breast cancer (i.e. 16%–29% full lifetime risk) over the age of 35 years, and for women at high breast cancer risk (i.e. ≥30% full lifetime risk) at any age.

The study found most women who did use a RRMed used tamoxifen (91%) and the most common age groups to initiate RRMed were 40-49 years (40%), followed by 50-59 years (26%).

Women at the highest risk of breast cancer ( ≥30% full lifetime risk) were more likely to use RRMed than other women (OR 1.82) – highlighting the importance of risk stratification and personal knowledge of breast cancer risk.

“There was weak evidence that uptake was more likely by women with more affected first-degree relatives (P = 0.06),” the study said.

The investigators, including Professor Kelly-Anne Phillips from the Peter MacCallum Cancer Centre, found no association between uptake of RRMed and parity or education.

They said previous kConFab research had shown that knowledge of an increased breast cancer risk would facilitate use of RRMed for most women (82%).

Concern about side-effects (31%) and inadequate information (23%) were the main reasons that women did not take preventive medication, the study found.

The study also found many GPs were unaware of RRMed or considered they had insufficient knowledge about these medicines.

The current study said the barriers to better use of RRMed were not unique to Australia.

“Tamoxifen was recently listed in the National Health Service Rapid Uptake Products programme, which aims to increase uptake of effective health interventions in the UK,” it said.

Note: The Peter MacCallum Cancer Centre hosts the online iPrevent program which includes a personalised breast cancer risk assessment calculator for women and information resources for clinicians.

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