Does Herceptin (trastuzumab) stop menstrual periods?

Yes, Herceptin (trastuzumab) treatment can cause periods (menstruation) to stop in a majority of premenopausal women, but some women will continue to have periods after Herceptin treatment.

How many women stop periods after Herceptin?

In a clinical trial called ALTTO 72.6 % women being treated with Herceptin reported that their period had stopped (treatment related amenorrhea) at their week 37 visit.

The ALLTO study looked at premenopausal women who had:

• histologically confirmed, completely excised, invasive non metastatic HER2-positive breast cancer and
• either node-positive or node-negative disease with pathologic tumor size of 1 cm or larger and
• had chemotherapy and
• treated with Herceptin (trastuzumab)

Does having your period stop after Herceptin change breast cancer risk?

Yes, having your period stop after Herceptin treatment does change your breast cancer risk survival risk. The ALLTO study results showed

• if your period stops then your six-year overall survival is higher at 95.6%
• if your period returns then your six-year overall survival is lower at 92.2%

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Are there disadvantages of having no period after Herceptin?

Although having no period may increase your survival statistics there are some disadvantages including

• infertility
• medication induced menopausal symptoms

These can be real concerns and if these are an issue for you, it is important to discuss these with your health care professional. Your health care professional can go through with you any risks and benefits of your treatment options, and what else can be done to reduce these issues.

Bottom Line:

• In the ALLTO study 72.6 % women being treated with Herceptin stopped having their period (treatment related amenorrhea)
• Patients in the ALLTO study who ceased periods had an increase in overall survival
• Patients in the ALLTO study who had periods had a decrease in overall survival
• Having treatment related amenorrhea (no period) can cause infertility and medication induced menopausal symptoms.