Smaller Babies for Women With, and After, Cancer

Kristin Jenkins

March 24, 2017

Women who have cancer as adolescents or young adults (AYA) and then go on to have children may have an increased risk for preterm birth and low birthweight (LBW), suggesting that additional surveillance of pregnancies in this population is warranted. The highest risk for preterm birth and low birthweight were seen in those who were pregnant at time of diagnosis.

These are the conclusions from a new population-based study published online March 23 in JAMA Oncology.

"Our results suggest that the increased prevalence of preterm birth and LBW may be most concentrated among births to AYA cancer survivors diagnosed during pregnancy, some of whom may deliver early to begin treatment," say the researchers, led by Hazel B. Nichols, PhD, assistant professor in the Department of Epidemiology at the University of North Carolina, Chapel Hill.

"However, modest though significant elevations in preterm birth and LBW remained among births to women diagnosed before pregnancy, indicating that the elevated prevalence of these outcomes may not be limited to births to women diagnosed during pregnancy," they add.  

Cancer survivors at highest risk for preterm birth and LBW were pregnant at the time of diagnosis, some having their baby early so they could start treatment, the study shows. Rates of adverse birth outcomes were highest for survivors of breast cancer (prevalence ratio [PR], 1.98), non-Hodgkin's lymphoma (PR, 2.41), and gynecologic cancer (PR, 2.74) and for those who received chemotherapy, the researchers say in their report.

A small but statistically significant increase in cesarean deliveries was also identified among survivors, although rates of preterm birth in women diagnosed with melanoma or thyroid cancer did not differ from those in women without cancer.

The new findings are in keeping with other reports, including another population-based cohort study from Western Australia showing similar increases in preterm birth and LBW in AYA cancer survivors compared with women without a previous cancer diagnosis.

Clinicians may want to rethink their preconception and prenatal counseling of AYA cancer survivors and to consider "the need for additional surveillance of pregnancies in this population," Dr Nichols and colleagues suggest.

In the United States, the 5-year relative survival rate for female cancer survivors diagnosed at 15 to 39 years of age is estimated to be 80%, the researchers point out. "With continued improvements in early diagnosis and treatment, a growing number of AYA patients with cancer will become long-term survivors, prompting concerns about the late effects of malignancy and treatment in this population."

Recent studies suggest that up to 60% of the more than 45,000 female adolescents and young adults in the United States who survive cancer each year want the option of having children.

"These findings were very positive in that we identified so many adolesent and young adult women who went on to have children after their cancer diagnosis," Dr Nichols told Medscape Medical News. "Our study provides population-based evidence for clinicians to weigh when deciding the appropriate follow-up schedule for prenatal care."

Patients with a history of cancer, especially if they have received chemotherapy, might need to be seen more frequently during pregnancy, Dr Nichols suggested. This would be similar to the care for patients with other risk factors for preterm birth, such as older maternal age, she said.

Study Details

For the case-control, cohort study, the researchers identified young female cancer survivors diagnosed between January 2000 and December 2013 from the North Carolina Central Cancer Registry. These records were then linked to state birth certificate files from January 2000 to December 2014 to identify 2598 women who gave birth after their cancer diagnosis. A random selection of 1299 women without cancer from the same state birth certificate files was matched for age and year of delivery.

In cancer survivors, mean age at diagnosis was 28.1 years, with a mean time of 3.1 years between diagnosis and giving birth. Melanoma skin/carcinoma was seen in 21%, thyroid cancer in 19%, breast cancer in 14%, melanoma in situ in 10%, Hodgkin's lymphoma in 7%, gynecologic cancers in 5%, non-Hodgkin's lymphoma in 4%, soft tissue sarcomas and central nervous system neoplasms in 3%, and carcinomas of the gastrointestinal tract in 2%.

More than half of cancer survivors (56%) were diagnosed with localized disease; 85% received surgery, 25% had chemotherapy, and 23% received radiation.

Cancer survivors treated with chemotherapy without radiation appeared to be most likely to have preterm and LBW infants compared with women without cancer, the researchers note.

Dr Nichols and colleagues also looked at the relationship between cancer types most commonly associated with adverse birth outcomes and the PRs by treatment type. In both breast cancer and non-Hodgkin's lymphoma survivors, treatment with chemotherapy without radiation resulted in the highest PRs for preterm birth (1.18 and 2.68, respectively) and LBW (1.78 and 3.31, respectively) compared with the noncancer cohort. In survivors of gynecologic cancer, PRs for preterm birth and LBW increased in patients who had surgery only (3.20 and 3.33, respectively).

When asked whether these findings might change current practice, Dr Nichols cautioned that many issues need to be addressed first, including how best to preserve fertility. "There is limited information available that is specific to women with a cancer history. Different chemotherapy agents may be more likely to affect the ovaries or the vascular system and may help us better understand how cancer treatment impacts future pregnancy."

This study was funded by the National Center for Advancing Translational Sciences and by a Faculty Development Award from the University of North Carolina Office of the Provost. Dr Nichols has disclosed no relevant financial relationships. Coauthor Carey K. Anders, MD, reports financial relationships with Novartis, Sanofi, toBBB, GERON, Angiochem, Merrimack, PUMA, Lily, Merck, Oncothyreon, Genentech, Nektar, Kadmon, UpToDate, and Jones & Bartlett Learning. The other authors have disclosed no relevant financial relationships.

JAMA Oncol. Published online March 23, 2017.  Abstract

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