Does Pregnancy Worsen Breast Cancer Outcome?

Does a Delay in Chemotherapy Affect Outcome?

Medscape: How close to standard protocols was treatment in the pregnant vs nonpregnant patients in your study? Guidelines^[1,2,3] and your own consensus statement^[5] recommend against giving tamoxifen during pregnancy, and trastuzumab (in HER2-positive patients) is contraindicated, so presumably these drugs were not given.

Prof. Amant: Tamoxifen is given after chemotherapy or after surgery and radiotherapy, so there is actually a place to give tamoxifen during pregnancy. Trastuzumab is a different story, of course, and there we have to acknowledge that this is the only kind of undertreatment in pregnancy. On the other hand, women can have this treatment after delivery and then it is very difficult to predict the loss of prognosis that delaying trastuzumab treatment causes. There is the potential that these women may do worse than otherwise, but that will be very difficult to prove, because you need a large group of women to study this. On the other hand, if there is an effect, I think it will be a small one and I think this is not sufficient basis to terminate the pregnancy.

Medscape: You mentioned delaying treatment. Women whose breast cancer is diagnosed in the first trimester are not usually given chemotherapy until the second or third trimester. Did your study indicate whether this delay might affect prognosis? Guidelines state that if chemotherapy needs to be started urgently during the first trimester, such as in metastatic disease, pregnancy termination should be discussed.

Prof. Amant: Our studies indicate that waiting a few weeks until starting chemotherapy is not detrimental for prognosis. Some studies have reported that if women wait for more than 3 months, then you start to see the prognosis worsen, but there are ample data showing that a few weeks' delay is not really a problem. So, that is what we tell our patients and what most oncologists believe. Administration of chemotherapy is not an emergency; you can delay it if necessary.

Pregnancy After Breast Cancer: Worse Prognosis?

Medscape: Your study involved only patients who had breast cancer diagnosed during pregnancy, not others who fall within the usual definition of PABC, such as those diagnosed within 1 year post-partum. It is suggested that these patients represent a distinct subgroup of patients from those with BCP and that they should be treated differently.^[4] Do you agree?

Prof. Amant: Yes, I agree with that. Before our study, the data on prognosis in BCP were conflicting, but the data on breast cancer diagnosed within 1 year of delivery all point toward a worse prognosis. So, these patients were not included in our study because we do feel that this is a separate group and that if you want good data, it is better to separate these groups.

Medscape: Are you looking at PABC patients in your registry?

Prof. Amant: Yes. This is an ongoing study at our center, but we need a larger group to provide more solid data.

Medscape: Is there any way to predict who might be diagnosed with breast cancer post-partum? One study found that nausea and vomiting during pregnancy was inversely associated with breast cancer risk, and the investigators suggested that it could reflect altered hormonal and metabolic profiles.^[10]

Prof. Amant: No, it is just an age effect for cancer during or after pregnancy. We do not think that there is a genetic issue there either. Of course, in very young women, you have to look into the family history because there might be a BRCA1 or BRCA2 mutation, but that does not differ in the post-partum group when compared with other cancers.

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