Among women under 50 with malignant melanoma, those diagnosed during or soon after pregnancy were significantly more likely to have tumors spread to other organs and tissues, and were also much more likely to have the cancer recur after treatment, the study found.Women diagnosed around the time of pregnancy were also more likely to die, though the risk increase wasn’t big enough to rule out the possibility it was due to chance.

“This study demonstrated that women who are diagnosed with melanoma during pregnancy or in the post-gestation period have higher risk melanomas,” said Dr. Jeffrey Farma, co-director of the cutaneous oncology and melanoma program at Fox Chase Cancer Center in Philadelphia, of the study, which was based on review of medical records for 462 women.

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“Although this is a retrospective small series, I believe consideration should be made to screening some patients more closely,” Farma, who wasn’t involved in the study, said by email.

While the study doesn’t examine why pregnancy might influence melanoma outcomes, it’s possible that hormone fluctuations or suppressed immune system activity during this time help tumors flourish, said senior author Dr. Brian Gastman, director of melanoma surgery at the Cleveland Clinic in Ohio.

To explore how pregnant patients fared with this type of cancer, researchers analyzed records for women who were all aged 49 and younger when diagnosed with melanoma between 1988 and 2012. This group included 41 women who were diagnosed during or within one year of pregnancy.

On average, the women were around 35 years old at the start of the study, and they were typically followed for at least seven years. Most of them were diagnosed with stage 0 or 1 melanoma. After treatment, 12.5% of the women diagnosed during or after pregnancy had the cancer return, compared with just 1.4% of the other women in the study. Metastasis occurred in 25% of women diagnosed around the time of pregnancy, compared with 12.7% of the others.

More women diagnosed around pregnancy died - 20% compared with 10.3% of the others - but this difference wasn’t statistically significant, the researchers report in the Journal of the American Academy of Dermatology, online January 20.

Because the study was based on patients at one medical center that tends to see more complex cases, it’s possible the results are not representative of what all women with melanoma might experience, the authors note.But the findings still suggest that doctors should advise pregnant women with melanoma to be hyper-vigilant about examining their skin for any changes or abnormalities and seek medical attention promptly if they see anything amiss, the researchers conclude.

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The best time to prevent melanoma, however, is before women even reach childbearing age, Gastman said by email.Parents should limit children’s exposure to sources of ultra violet (UV) radiation that can cause skin cancer by making sure kids have sunblock or protective clothing. Parents should also educate older kids – particularly teen girls – about the melanoma risk associated with tanning beds.

“We know melanoma is rising in young women more than in young men,” Gastman added. “We also know that the die may be cast (in terms of getting melanoma) during childhood. So combining all of this, this is as much a parental issue in caring for young female children as it is for young women.”