Sweden is famous for keeping extensive social and health registries for its citizens. Data from no less than six registries were put to use for a study by the Karolinska Institute, which showed that Hodgkin lymphoma survivors who become pregnant during remission do not have an increased risk of relapse. The study was published online in the Journal of Clinical Oncology (2016;34:337-344).
Among 449 women diagnosed with Hodgkin lymphoma between 1992 and 2009, 144 women (32 percent) had at least one pregnancy while in remission following treatment.
“There was no evidence that the pregnancy increased the relapse rate,” was the conclusion reported by first author Caroline E. Weibull, a doctoral student, and colleagues in the Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden.
Whether this information is useful to practitioners was questioned by one U.S. expert.
Patricia Ganz, MD, Professor of Medicine and of Health Policy and Management, David Geffen School of Medicine at UCLA, and Director of the Center for Cancer Prevention & Control Research at the Jonsson Comprehensive Cancer Center, was asked to comment on the study for OT.
“This is a well-conducted study, but I am not sure that this changes our practices, since advice regarding risk for recurrent HD with pregnancy has not been a major clinical or survivorship concern from my experience,” Ganz said. “We might worry about cardiac risk with pregnancy if there was a lot of anthracycline or chest radiation exposure, but not a risk for relapse.”
The Swedish researchers acknowledged that previous studies in Hodgkin lymphoma have suggested reproductive patterns before diagnosis do not have a negative effect on its incidence or prognosis (Eur J Cancer2013;49:3686-3693), and being pregnant at the time of diagnosis does not affect prognosis or survival (J Clin Oncol2009;27:45-51).
Even so, they listed two plausible biologic mechanisms by which pregnancy might increase the risk of relapse: an inflammatory reaction with a Th2 profile predominance, and an increase in number of inhibitory regulatory T cells considered essential for pregnancy to prevent rejection of the fetus.
“In studies of the etiology of Hodgkin lymphoma, skewing the T-cell response toward a Th2-type microenvironment is believed to support B-cell survival and thus induce tumor cell proliferation in Hodgkin lymphoma,” they wrote. “In turn, regulatory T cells, which are increased in pregnant women, are thought to suppress the tumor-protective cytotoxic T lymphocytes needed in early clearance of HL precursor cells.”
Furthermore, they said previous studies have indicated patients fear that a pregnancy could induce relapse (Hum Reprod2014;29:2704-2711).
“Given the clinical importance of this question, and the lack of empirical evidence, we undertook this investigation into whether an association exists between recent pregnancy and relapse in women in whom Hodgkin lymphoma is diagnosed and who are treated with modern regimens.”
The study data were obtained from the Swedish Cancer Registry, National Database of Hodgkin Lymphoma, Swedish National Inpatient Register of all stem-cell transplantations in the country, the Swedish Medical Birth Register, Register of Total Population and Population Changes, and the Swedish Cause of Death Register.
In an email, Ganz elaborated in her comments regarding Hodgkin lymphoma survivors and relapse due to pregnancy.
“Frankly, this is not an issue that I have ever had any concern about,” she said. In fact, she and colleagues strongly advocated for chemotherapy with the ABVD regimen (doxorubicin, bleomycin, vinblastine, dacarbazine) rather than MOPP (mustargen, vincristine, procarbazine, prednisone) to preserve fertility.
Ganz speculated the motivation for the study seemed to be a very old literature where this issue was raised, but reiterated she has not been familiar with risk for relapse ever being an issue during her career.
She added that many of the papers cited in this study regarding whether or not it is possible or safe to have a child after cancer relate more to the potential harm to ova or sperm, and to the health of potential offspring. This has been largely addressed in earlier literature she cited, where harmful subsequent effects on offspring have not been noted (J Clin Oncol 1993;11:507-512).