Clinical consultations and investigations before and after discontinuation of endocrine therapy in women with primary breast cancer.

Objective: Although clinical trials recommend that women with hormone-dependent primary breast cancer remain on endocrine therapy for at least 5 years, up to 60% discontinue treatment early. We determined whether these women had consulted with clinicians or had investigations for cancer recurrence or metastasis around the time they discontinued endocrine therapy, and whether clinical contact continued after discontinuation.

Methods: We performed case-control and cohort studies of women from the 45 and Up Study who were diagnosed with invasive primary breast cancer between January 2003 and December 2008, and who had ≥12 months of anastrozole, exemestane, letrozole or tamoxifen subsequently dispensed.

Results: Women who consulted general practitioners and surgeons/oncologists, and women who had breast ultrasound/mammogram were just as likely to discontinue endocrine therapy within 30 days as those who did not consult these clinicians or have this investigation. In the 6 months after early discontinuation, women who discontinued endocrine therapy were less likely to consult general practitioners (adjusted risk ratio [RRadj] 0.80; 95% confidence interval [CI] 0.75, 0.86) and surgeons/oncologists (RRadj 0.62; 95% CI 0.54, 0.72) than those who remained on therapy.

Conclusions: For most women, endocrine therapy discontinuation did not appear to follow consultation with doctors managing their breast cancer treatment or investigations for recurrence or metastasis. However, women who discontinued endocrine therapy were less likely to consult their general practitioner or surgeon/oncologist in the 6 months following discontinuation than those who remained on therapy. Of the clinician groups studied, general practitioners are best placed to engage and support women to continue pharmacotherapy. However, mechanisms are needed to prompt clinicians to do this at every visit.