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Posted by on Nov 30, 2020 in Breast cancer | 0 comments

In a nutshell

This study compared the safety of two hormonal medications used to treat breast cancer, tamoxifen (Nolvadex) and letrozole (Femara). This study found that tamoxifen was associated with an increased risk of blood clots, while letrozole was associated with an increased risk of angina and heart attacks.

Some background

Hormone-positive breast cancer describes a tumor that grows in response to female sex hormones. These hormones are estrogen or progesterone. This type of cancer can be treated with drugs that block the effects of these hormones. 

Tamoxifen and letrozole are both used to treat hormone-positive breast cancer.  They work against the hormones in different ways. Letrozole is usually used first because it has been shown to be more effective. However tamoxifen is still used a lot, or the two drugs can be used in sequence.  Both drugs can be associated with heart problems and blood clots but it is not clear which one is safer.

Methods & findings

6,144 patients with breast cancer were treated with combinations of tamoxifen and letrozole. Group 1 received tamoxifen for 5 years. group 2 received letrozole for 5 years. Group 3 received tamoxifen for 2 years then letrozole for 3 years and group 4 received letrozole for 2 years then tamoxifen for 3 years.  Patients were monitored for an average of 45.8 months for problems including heart attack and blood clots.

6.5% of patients in the study developed a heart problem, with 2.4% having serious heart problems. Patients in group 2 had the highest risk of heart problems such as angina or heart attack. This group was 83% more likely to develop a heart problem than group 1. 

Age over 65 years, a history of smoking, obesity, high blood pressure, or previous heart problems, including blood clots, were associated with a greater risk of heart complication from hormonal treatment.

4.1% of patients in this study developed a blood clot-related complication. Patients on tamoxifen treatment alone were 2.1 times more likely to develop a blood clot than patients on letrozole-only treatment.

The bottom line

This study showed that letrozole treatment was associated with an increased risk of angina or heart attack, while tamoxifen treatment was associated with an increased risk of blood clots.  

The fine print

This study was funded by Novartis, the manufacturer of letrozole.

Published By :

Breast Cancer Research and Treatment

Date :

Nov 08, 2020

Original Title :

Cumulative incidence of cardiovascular events under tamoxifen and letrozole alone and in sequence: a report from the BIG 1-98 trial.

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