Treatment for most cancers in girls and women younger than 39 years significantly reduces the likelihood of subsequent pregnancy a large population study now shows.
Cancer survivors were 38% less likely to achieve a pregnancy compared to women in the general population, an impact of cancer treatment seen across almost all diagnostic groups and all ages, says a research group led by Richard Anderson, MD, PhD, from the MRC Center for Reproductive Health, Queen's Medical Research Institute at the University of Edinburgh, United Kingdom.
The study showed that 20.6% of cancer survivors achieved a first pregnancy after cancer diagnosis (2114 first pregnancies in 10,271 women), compared to 38.7% in control persons.
Women with cancer were about half as likely to achieve a first pregnancy after diagnosis as were controls. Dr Richard Anderson
"Thus, women with cancer were about half as likely to achieve a first pregnancy after diagnosis as were controls," said Dr Anderson. He presented the study on July 3 at the annual meeting of the European Society of Human Reproduction and Embryology in Geneva, Switzerland.
"This analysis provides robust, population-based evidence for the extent of the effect of cancer and its treatment on subsequent pregnancy across the reproductive age range," the study authors say. "The major impact on subsequent pregnancy in some common cancers highlights the need for enhanced strategies to preserve fertility in girls and young women."
Dr Anderson and colleagues note that the study findings are limited by the fact that they could not assess the impact of treatment on fertility because details about participants' treatment were not available. In addition, follow-up was limited for women diagnosed in the most recent period.
The impact of cancer therapy on subsequent pregnancy remains a significant issue, Dr Anderson commented to Medscape Medical News. With the increased number of young female cancer survivors and improved techniques for fertility restoration, such as cryopreservation of eggs and ovarian tissue, "there is a major need to improve access to fertility preservation and to identify those women [and girls] at risk," he said.
Approached for comment, Daniel M. Green, MD, of the Departments of Epidemiology and Cancer Control at St. Jude Children's Research Hospital in Memphis, Tennessee, told Medscape Medical News that the study "is confirmatory of several other population-based studies, primarily from the Nordic countries and one recently published from North Carolina." However, he noted that "the absence of exposure information is a significant weakness. This abstract does not add to our understanding of post-therapy fertility among survivors of childhood, adolescent, or young adult cancer."
Dr Green is coauthor of the Childhood Cancer Survivor Study, a multicenter research initiative that investigated long-term clinical outcomes in 14,000 5-year survivors of childhood and adolescent cancer diagnosed between 1970 and 1986.
For their cohort study, Dr Anderson and colleagues identified 23,201 female patients from the Scottish Cancer Registry who were first diagnosed between 1981 and 2012 and who subsequently became pregnant. All were 39 years of age or younger at the time of diagnosis. Pregnancies were included to the end of 2014.
The cancer registry records were cross-linked to hospital discharge records to calculate standardized incidence ratios (SIRs) for pregnancy. The calculations were standardized for age and year of diagnosis. A subgroup of cancer survivors who had not been pregnant prior to their cancer diagnosis was created for comparison with a matched control group of women from the general population. Additional analyses were performed for patients diagnosed with breast cancer, Hodgkin's lymphoma, and leukemia.
Cancer survivors achieved fewer pregnancies — 6627 observed compared to 10,736 expected pregnancies. A reduction in SIR was observed for women across almost all cancers. The SIR ranged from 0.34 in those with cervical cancer to 0.87 for women diagnosed with skin cancer. It was lowest in women from the most deprived quintile.
The reduced SIR in female cancer survivors was seen across all age groups, and it fell progressively with age at diagnosis.
The time frame in which diagnosis took place also had a strong impact on SIR. Women who were diagnosed with cancer in the period between 1981 and 1998 had an SIR of 0.47 compared to those diagnosed between 2005 and 2012, who had an SIR of 0.64 and higher pregnancy rates. This suggests that the impact on fertility of some cancer treatments is not as severe as it was previously, the study authors say.
The most significant reductions in pregnancy rates were seen in survivors of breast cancer (SIR, 0.44), leukemia (SIR, 0.30), and Hodgkin's lymphoma (SIR, 0.65). Pregnancy rates were favorably affected by more recent treatment for women with Hodgkin's lymphoma, but not for those with leukemia or breast cancer.
The proportion of first pregnancies that ended in termination was lower among women with previous cancer than among control persons (11.2% vs 14.7% of pregnancies), but no differences were observed in the risk for either miscarriage or stillbirth.
"This study provides further evidence that cancer and cancer treatment are associated with achieving fewer pregnancies," said Jessica R. Gorman, PhD, MPH, of the School of Social and Behavioral Health Sciences at Oregon State University College of Public Health and Human Sciences, in Corvallis. "It is interesting to note that this was the case for all age groups and most cancers." However, she added in an email, "more research is needed to explore the reasons for this outcome."
Dr Gorman is coauthor of a 2016 study of young female cancer survivors and their use of fertility care after completing cancer treatment. Results showed that many of the women did not feel they had received enough information about fertility care, despite the fact that they wanted to have children.
"To improve fertility outcomes for female cancer survivors, it is important to offer fertility consultation both at the time of cancer diagnosis and after completing treatment, when survivors may be more prepared to discuss family building options," Dr Gorman told Medscape Medical News. In addition to information about fertility and parenthood options, women treated for cancer need guidance and support from healthcare providers to navigate "both the emotional and practical issues that arise when considering their family building options," she said.
These conversations can be difficult, acknowledged Nancy Baxter, MD, PhD, chief of the General Surgery Department at St. Michael's Hospital and professor of surgery at the University of Toronto, Canada. Dr Baxter is lead author of a 2013 Canadian population-based study showing that recurrence-free survivors of nongynecologic malignancies who were 20 to 34 years of age were less likely than control persons to experience childbirth after diagnosis. Although the overall effect was small, it was influenced by prediagnosis childbirth and malignancy type.
These conversations have to occur when patients may already be feeling overwhelmed by their diagnosis and their pending treatment, Dr Baxter told Medscape Medical News. "Although fertility preservation is not a guarantee, the options can increase the chances of future fertility and do not need to result in major delays in treatment, so are possible for most women at risk."
To make things easier, she pointed out, a decision aid called BEFORE is being developed to help women understand their risks and options. It will point to resources and help guide patient-doctor conversations. A version for women with breast cancer is almost ready for use.
Clinicians also need to find out whether individual patients want to pursue fertility preservation, Dr Baxter said, adding, "Not every woman wants to have children.
"As doctors, we need to be looking further ahead and focusing not only on curing our patients but also on how we can help their lives after cancer be as normal as possible," Dr Baxter told Medscape Medical News. "We have made great strides, but there is definitely more work to be done."
No funding has been disclosed. The study authors, Dr Green, and Dr Gorman have disclosed no relevant financial relationships. Dr Baxter has a relationship with Servier Canada Inc.
European Society of Human Reproduction and Embryology. Abstract O-082, presented July 3, 2017.