Study examines maternal and newborn health risks and colorectal cancer

In one of the first studies to examine maternal and newborn health risks and colorectal cancer, UC Davis researchers have found that women diagnosed with the disease during or shortly after their pregnancies have the same survival as women who have the disease and are not pregnant.

The study also found that, while there is an increased chance of preterm labor, the outcomes for the babies is the same for women with colorectal cancer as for those without the disease.

"We see a few cases of this every year, but there has been very little information so far on whether colorectal cancer discovered during or just after pregnancy leads to different outcomes. Our study clarifies these issues so physicians can confidently provide guidance to patients," said Lloyd Smith, a gynecologic oncologist with the UC Davis Cancer Center and senior author of the study.

The study, which will appear in the March issue of The Journal of Maternal-Fetal Health and Neonatal Medicine , used information gathered over an eight-year period from linked state of California databases on hospital discharges, birth records and cancers. Researchers compared information on 106 women diagnosed with colorectal cancer during or up to one year after pregnancy with two other groups. The first group included age-matched pregnant women without colorectal cancer. The second group included age-matched, non-pregnant women with colorectal cancer. A range of factors were considered, including demographics, treatment, onset of prenatal care, insurance type, tumor subtype and survival times.

The team found no significant distinctions in the comparisons, including survival times for the women with cancer, which were nearly identical — 43 percent in the pregnant group and 44 percent in the non-pregnant group. There was a two-fold increase in preterm labor and premature deliveries among women with colorectal cancer, however this had no affect on newborn health or survival.

"We're not sure why there were early deliveries in women with colon or rectal cancer. It could be related to a pregnancy-associated bacterial infection or an inflammatory response linked to the cancer. More research is needed to get to the cause of this tendency," Smith said.

The current study is one in a series from UC Davis aimed at learning more about cancers and pregnancy with the goal of giving reliable information to ob/gyns who manage patients with cancer. The researchers previously analyzed data on pregnancy-associated breast, skin, thyroid, cervical and ovarian cancers. Expected to be published in the future are studies on leukemia, lymphoma and brain and cervical cancers.

"The common finding across all of the studies so far is that most cancers escape detection during pregnancy and are typically discovered after delivery," said Smith, who is also chair of obstetrics and gynecology with UC Davis. "So far only breast cancer survival is negatively impacted by pregnancy, most likely due the stimulative effect of pregnancy hormones on the cancer."

The results of the current study should be reassuring to patients with pregnancy-associated colon or rectal cancer, however Smith advises greater awareness of cancer symptoms.

"There really were no obvious findings indicating where we could improve care, with the exception that physicians should be on the lookout with their pregnant patients for colon and rectal cancer symptoms," he said. "Rectal bleeding during pregnancy is often blamed on hemorrhoids. We should always be aware of the possibility of a tumor, even in young women."

Lead author Mary Dahling, a UC Davis medical resident when the study was conducted, also recommends additional prenatal services for women with family histories of cancer.

"Even though the obstetrical and neonatal outcomes for women with colorectal cancer were good, we should be sure to include genetic counseling in the range of services offered to women who are considering getting pregnant, especially if there is a genetic susceptibility for the disease," said Dahling, who is now in private practice in Minneapolis.