Cancer and pregnancy

Do cancer during pregnancy influence the prognosis? Is the risk of pregnancy and delivery complications increased for women with pregnancies after cancer? If pre-eclampsia have protective effects on the life-time risk of getting breast cancer, do breast cancer survivors with a history of pre-eclampsia have a better prognosis than those without pre-eclampsia in the past?

Last updated: 2020-09-14

Background and purposes

Maternal health related to pregnancies after cancer

Cancer and pregnancy have often been associated with negative influence both ways. We have sparse knowledge about maternal health during pregnancies and deliveries after a cancer diagnosis, and what kind of follow-up those women should have. There are few studies on this topic, and most of them are small and with selected patient groups. Pregnant cancer survivors have a slightly higher risk of preterm birth and a baby with low birth weight at term. We want to explore if post-cancer pregnancies gives a higher risk of pregnancy and delivery complications. Recent studies have shown that most babies born of cancer survivors, not seem to be affected by their mothers disease or cancer treatment, and that maternal prognosis in general not are affected by a post-cancer pregnancy.

Breast cancer in relation to pregnancy

Breast cancer diagnosed during or shortly after a pregnancy have in the past been looked upon as associated to a poorer cancer survival. There are few large, population-based studies on this, and the findings are contradictory. Larger studies are often lacking prognostic factors or treatment information, and hospital-based studies are often based on selected patient materials. We want to assess if the prognosis for women diagnosed with breast cancer associated to a pregnancy really is poorer than for women without a pregnancy related to their cancer diagnosis.

Pre-eclampsia and later breast cancer

Pre-eclampsia seem to protect women for future breast cancer, the incidence have been found lower for those with this pregnancy complication. Yet, it is unknown if the prognosis is better among women with a history of pre-eclampsia who get diagnosed with breast cancer, compared to women with breast cancer but without earlier pre-eclampsia. Mapping of prognostic factors among women with breast cancer after pre-eclampsia or gestational hypertension might increase our knowledge about the development of pre-eclampsia and its protecting effect of breast cancer.

Design, method and material

This study is a population-based study with information about cancer patients in Norway, diagnosed at maximum age 45 in the period 1967-2014, with information about all pregnancies in the same period. Data is extracted from The Cancer Registry of Norway and the Medical Birth Registry at the Norwegian Institute of Public Health.

Breast cancer is focused in two of the substudies, while all cancer types affecting young adult women will be analyzed separately and combined for the study about maternal health related to post-cancer pregnancies. The most common cancer types in this age group is malignant melanoma, cervical cancer, breast cancer, ovarian cancer, thyroid cancer, brain tumors, lymphoma and leukemia.