‘Reassuring’ data on HRT in women with cancer

Medicines

By Geir O'Rourke

1 Jul 2024

Hormone replacement therapy is not associated with increased cancer-specific or all-cause mortality in women with common cancers including lung, colorectal and melanoma, a registry study has found.

The authors say their data should provide some reassurance but must be interpreted with caution, given the results conflict with previous recommendations, based on preclinical and other evidence, that patients with some cancers should avoid HRT.

Some 180,000 UK women newly diagnosed with 17 site-specific cancers from 1998 to 2019 were included in the study, which did exclude breast cancer, for which HRT is contraindicated.

Overall, 7% of patients used systemic HRT after their diagnosis, while linked mortality records showed there were 54,861 cancer-specific deaths over follow-up, which continued until either early or late 2020, depending on location.

Statistical analysis showed no evidence of cancer-specific mortality among HRT users in any of the 17 cancer sites studied, with HRT use associated with lower risk of cancer death in six cancers including colorectal, ovarian, kidney and non-Hodgkin lymphoma.

Writing in British Journal of Cancer (link here), the authors did stress there were some caveats around that latter result, noting the analysis of uterine and kidney cancers were based on relatively small numbers, and the association did not follow a dose-response in some of the other cancers.

Associations were also generally similar overall in analyses additionally adjusting for BMI, the investigators said.

Other limitations to the finding included potential confounding due to the possibility that cancer prognosis may influence a patient’s likelihood of receiving HRT, while there was a particular risk of confounding by indication in women with oestrogen-sensitive cancers such as uterus, ovarian and cervical cancer, according to the authors.

They noted earlier reviews of the oncologic safety of HRT had recommended that patients with bladder, lung, brain and gastric cancer should avoid the treatment, while small RCTs in patients with ovarian, endometrial and other cancers had produced mixed results.

With respect to lung cancer, the current study had also demonstrated a slight association with increased cancer-specific mortality in a sensitivity analysis comparing users of systemic HRT with users of vaginal oestrogen therapy, the authors added.

Nevertheless, the results could offer “some reassurance” to clinicians and patients of the safety of systemic HRT in women with one of the 17 cancers studied, they wrote.

“Along with other known risks associated with HRT use, our findings may contribute to the decision of cancer patients, and their prescribers, to use HRT,” the authors concluded.

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