Should breast cancer survivors double the length of time they take tamoxifen for only a potentially small chance of avoiding recurrence?
As reported by the New York Times, here are the results from the Tamoxifen study:
… In the group assigned to take tamoxifen for 10 years, 21.4 percent had a recurrence of breast cancer in the ensuing 10 years, meaning the period 5 to 14 years after their diagnoses. The recurrence rate for those who took only five years of tamoxifen was 25.1 percent.
About 12.2 percent of those in the 10-year treatment group died from breast cancer, compared with 15 percent for those in the control group…
“The treatment effect is real, but it’s modest,” said Dr. Paul E. Goss, director of breast cancer research at the Massachusetts General Hospital.
But is the effect real? The reported treatment differences are quite small.
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The reporting on this follow-up study of the ATLAS study was poor. The adverse effects of extended tamoxifen treatment, for example, included a 87% increased risk for pulmonary embolism and 74% increased risk for endometrial cancer. Remember, after 8 years of follow-up, the ATLAS trial found no significant difference in either the recurrence or deaths between the groups, the benefit only apparently appeared after year ten.
Also, note that it compared Tamoxifen to Tamoxifen — NOT tamoxifen to newer and potentially better drugs. Post menopausal women, for example, are usually given newer drugs called aromatase inhibitors, following or instead of a shorter treatment with tamoxifen, because at least half of recurrences with ER (estrogen receptor) positive cancers occur after 5 years. The MA 17 trial of the aromatase inhibitor, letrozole, in postmenopausal breast cancer patients found better 10 year survival compared to tamoxifen, with a significant reduction in mortality among the node-positive subgroup.
But there is not enough clinical research currently available for a doctor or woman to base a decision on the various treatment options available, such as if a period of one drug then another or some combination might be better. If there was a helpful take-away from this story, it’s that we should be looking at longer cancer survivals than 5 years out when looking at the benefit-risks of various treatments.
The doctor who hosted the press conference of this latest news story said the ATLAS results are most relevant for younger women, but that tamoxifen still might not be best for every premenopausal women, such as those with grade 1 cancers.
But we didn’t hear that there may also be newer and better treatment options. For example, among premenopausal women with breast cancer, a small study of 452 patients just published in BMC Cancer compared tamoxifen with a new medication with a better risk-benefit profile called toremifene. It found that recurrence free surival was better with the new drug, with 5 deaths in the tamoxifen versus 0 deaths in the toremifene group.
So, while ABC News and the other mainstream media headlines were shouting that extending tamoxifen can save lives, like everything in the news, it should taken cautiously.