BARCELONA—There is no evidence that pregnancy is detrimental to patients who have survived breast cancer, according to a meta-analysis presented here at the European Breast Cancer Conference. The study was conducted by Belgian, Italian, and Greek investigators and included 14 studies undertaken between 1970 and 2009 among a total of nearly 20,000 women.
“What we found—contrary to the perception of the medical community—was that women who got pregnant following a breast cancer diagnosis actually had a longer survival,” Hatem Azim, MD, of the Jules Bordet Institute in Brussels, said in an interview.
The 1,417 patients in the study who became pregnant after a diagnosis of breast cancer had their risk of death reduced by 40% on average compared with patients in the control group of 18,059 breast cancer survivors who did not become pregnant, suggesting a protective effect of pregnancy. Still, Dr. Azim cautioned, that needed to be interpreted with caution because of possible selection bias, since the women who got pregnant were generally relapse-free.
But because of this potential bias, his team then analyzed data from three studies selecting controls who were relapse-free between diagnosis and conception, and the results still showed positive data for the effect of pregnancy—“which means that even if we control for relapse, women who get pregnant following breast cancer diagnosis have a better outcome,” he said.
He acknowledged that it is still not known for certain that pregnancy is protective, but he strongly endorsed the policy of not denying women who want to get pregnant the option of doing so, especially on grounds of maximizing their quality of life.
When to Get Pregnant
Dr. Azim thought, however, that clinicians need to make use of their knowledge and judgment to advise patients about the best timing of any desired pregnancy following successful treatment for breast cancer. Any adjuvant hormonal therapy should be completed first, but even if endocrine therapy is not used at all, he still recommended a waiting period before trying for a baby.
“For the time being—in my opinion—waiting for at least two years is the wisest idea,” he said.
Commenting on the data presented by Dr. Azim, Martine Piccart, MD, PhD, Head of Medicine at Jules Bordet Institute in Brussels, described the finding as “giving a lot of hope to young women with breast cancer.” Dr. Piccart told OT that putting all the small studies together to get more robust evidence was a very good idea. And she thought that, not forgetting the potential bias, the data seem to indicate that women do even better because of pregnancy.
Clinicians need, though, to pay attention to the choice of drugs given, she noted: “Some drugs should clearly be avoided—the ones that interfere with ovarian function.” And she suggested that the issue of subsequent pregnancy now needs to become part of the initial discussion doctors have with young women diagnosed with breast cancer.
Unfortunately, in another study reported at the meeting, patients newly diagnosed with breast cancer who had completed pregnancy within the previous year had a significantly worse prognosis when compared with patients who were not pregnant or had a current pregnancy, whether or not the pregnancy was completed to term.
Angela Ives, DipAppSc, MSc, PhD, of the University of Western Australia, reported that while the survival of patients who were currently pregnant at the time of cancer diagnosis was similar to those who were not, patients who had completed either full-term pregnancies, or had terminations or miscarriages within the previous 12 months were found to be 48% more likely to die.
The study took data from 2,752 women under age 45 who were diagnosed with breast cancer between January 1982 and December 2003; a total of182 had gestational breast cancer—i.e., breast cancer diagnosed while the woman is pregnant or up to 12 months postpartum—of whom 55 had current pregnancies and 127 had completed pregnancy within 12 months of diagnosis.
The increased risk remained after adjustment for lymph node status, disease stage at diagnosis, histological tumor grade, and age.
While Dr. Ives acknowledged that more research is still needed, she concluded that pregnancy plays a role in breast cancer prognosis and she advised clinicians to keep it in mind: “If a woman has symptoms that could be attributed to breast cancer, it's really important to investigate promptly,” she said.
Chemotherapy: No Harm to Fetus
There was encouraging news reported about the use of chemotherapy in patients who are currently pregnant: In a study of registry data from 235 patients collected prospectively (119) and retrospectively (116), the German Breast Group reported that chemotherapy caused no fetal harm.
In an interview Sibylle Loibl, MD, PhD, said that the study confirmed earlier findings from smaller studies.
The investigators collected data from women age 23 to 46 (median 33) diagnosed with breast cancer during pregnancy between April 2003 and October 2009, noting factors such as stage, tumor biology, and the use of surgery. Outcomes among 91 babies exposed to chemotherapy were compared with outcomes in 60 babies whose mothers received no chemotherapy.
Most patients were diagnosed during the second trimester of pregnancy, and chemotherapy was given with a median of four cycles (1 to 6 cycles) of mainly anthracycline-based regimens.
There was no statistically significant difference between the two groups in birth weight, time of delivery, and hemoglobin, whether or not the mother had chemotherapy for her breast cancer.
“We strongly recommend that the patient should be treated as closely as possible with standard treatment,” Dr. Loibl said.
When she was asked, however, if there was any indication at all that pregnant patients should be treated differently she noted that clinicians still have to keep in mind that they must deal with both the mother and the fetus: “You have to check the fetus regularly, make sure there is no growth retardation.”
Dr. Loibl also pointed out that care needs to be taken with taxane therapy as not so many data are available on this, and she noted that it is not recommended to use either trastuzumab or any kind of endocrine treatment with these patients, but that radiotherapy is probably OK.
Within those caveats, Dr Loibl recommended that doctors treat pregnant patients in the same way as those who are not pregnant. Commenting on those German findings, Dr. Azim said he thought there were some important practical messages for busy cancer doctors: firstly that pregnant patients should not have chemotherapy during the first trimester, because this is the period of organogenesis and is associated with up to a 20% incidence of fetal malformations.
He said he was impressed with the data on anthracycline-based regimens and echoed Dr. Loibl's concern that data on taxanes are insufficient to draw conclusions.
“A main issue of dealing with these women is that we'll never have a high level of evidence because we'll never have a randomized trial and never have a large number of patients, because this is relatively rare,” he noted.
The researchers talk more about this topic in an OT Broadcast News interview with Peter Goodwin, accessible on the Podcast link at http://oncology-times.com, or via iTunes.