Being diagnosed with cancer during your pregnancy is rare. Cancer diagnosis occurs in only a fraction of the population, about one in 1,000 pregnancies. Research is lacking, so there is very little proven fact to guide patients and doctors down the proper treatment path. We do know, however, that a woman who is diagnosed with cancer during pregnancy can carry the fetus to term and deliver a healthy infant. Cancers typically affect only the mother, though some forms like melanoma have been known to spread to the placenta. The placenta is an organ that grows during pregnancy and is shed immediately after pregnancy. Despite the fact that the placenta may be affected, most cancers will not affect the fetus.

Doctors have found that cancers affecting pregnant women tend to be the cancers that affect the younger population. For instance, cancers of the cervix, breast and thyroid are more common. One form of cancer directly associated with pregnancy is gestational trophoblastic tumor. This condition most often occurs when the sperm and egg join improperly, though the condition has developed during a normal pregnancy.

Age tends to be a precursor for some forms of cancer and thus, as women wait longer to start a family, more and more cancers are popping up during pregnancy.

Diagnosing Cancer During Pregnancy
Pregnancy can actually make it harder to diagnose cancer early. Some of the most common cancer symptoms look a lot like pregnancy-related side effects, including bloating of the abdomen and frequent, recurring headaches. When these symptoms arise during pregnancy they are considered normal, not abnormal.

The most common cancer diagnosed during pregnancy is breast cancer. About one out of every 3,000 pregnant women is diagnosed with breast cancer. Enlarging of the breast tissue during pregnancy can make it difficult to diagnose breast cancer, especially smaller tumors hidden by breast growth. Mammograms are not performed as part of a regular prenatal series of diagnostic tests.

If your doctor suspects cancer has developed, there may be some concern about some diagnostic tests like x-rays. The amount of radiation delivered to the body during a diagnostic  x-ray is minimal. According to research studies, the fetus is not harmed during a typical diagnostic x-ray. There is a protective pad that can be placed over the fetus and uterus before the x-ray is taken. This blocks some of the radiation to prevent negative side effects. Other tests like the magnetic resonance imaging (MRI), biopsy and ultrasound are safe during pregnancy and should not cause alarm.

There are times when diagnostic tests performed during pregnancy reveal a previously undetected cancer like cancer of the cervix or ovaries when normal prenatal testing is completed. Normal prenatal tests that may detect cancer include the ultrasound and Pap smear.

Treating Cancer During Pregnancy
Once the diagnosis of cancer is made, you will need to discuss treatment with your doctor. The final decision on treatment is yours, but talk through all options to find the best option for you and your unborn child. When choosing safe treatments the doctor will take factors like age of the fetus, type of cancer, location of cancer and size of the cancer into consideration. The first 12 weeks of pregnancy is the most crucial in terms of fetal health. This is the time frame when the fetus is most likely to be affected by a cancer treatment. The mother may choose to delay cancer treatment until the latter second or third trimester to protect the fetus. If the cancer diagnosis is made in the latter months of pregnancy, treatment may be delayed until baby is born. In some cases, labor will be started early so mom can start treatment.

The three treatments that require the most discussion are:

  • Radiation
  • Chemotherapy
  • Surgery

These treatments are viable for the pregnant patient, but they are also more dangerous than other treatments and should be considered as an alternative to less invasive treatments when possible.

Surgical Treatment
Surgery is used to remove the cancer from the body before radiation or chemotherapy is started. This treatment is typically reserved for tumors and the tissues that surround the tumor. Surgery is safe during pregnancy and may eliminate the need for chemotherapy and radiation.

Chemotherapy Treatment
Chemotherapy is the use of medications to eliminate cancer cells. The drugs stop the cancer cells from splitting, dividing and growing. If chemotherapy is used during the first 12 weeks of pregnancy it can affect the health of the fetus – so doctors tend to wait until latter stages of gestation if possible. There have been cases of birth defects and fetal death associated with chemotherapy.

If chemotherapy is administered during the second or third trimesters of pregnancy, the fetus may not be directly harmed by the drugs, but there could be side effects of treatment that indirectly harm the fetus. For instance, some cancer drugs cause anemia and extreme nausea. In these cases the fetus is affected by the impaired health of the mother. In other cases lowered red blood cell counts can affect the pregnancy. Often, infants born to mothers who’ve undergone chemotherapy during pregnancy are born early and weight less than peers born to healthy mothers.

Radiation Treatment
Radiation is one of the potentially riskiest cancer treatments for the fetus, especially if it's directed towards the abdominal area and the uterus. The cancer cells are flooded with radiation, essentially killing the cells and surrounding tissues. The fetus can be harmed during therapeutic radiation and most doctors will avoid radiation therapy especially during the first trimester. If radiation therapy involving the lower abdomen is needed it will likely be performed during the second or third trimester of pregnancy.

Breastfeeding with Cancer
While there is no risk of passing cancer cells to baby through breast milk, there is a chance of passing cancer drugs and treatments to baby. Oncologists suggest avoiding breastfeeding during cancer treatment whenever possible. If breastfeeding is the only option, the patient must talk with the oncologist about treatments that are safe for the infant.

Does Being Pregnant Affect the Outcome of Cancer Treatment?
There is no indication that pregnancy changes the outlook or prognosis for cancer recovery. Of course, there are many factors to consider, including the stage of cancer, type of cancer and whether or not cancer treatment is being delayed until the latter stages of pregnancy or until the infant is born. However, there are certain forms of cancer that may progress and grow faster during pregnancy because of increased hormones. This is true of malignant melanoma and may be true of other forms of cancer.

Getting Pregnant After Cancer
Surviving cancer is something to celebrate. If you want to start a family and you’ve survived cancer, there is little reason to wait. It is important to discuss pregnancy and your cancer with the oncologist before attempting to conceive as some cancers are affected by hormone levels, as stated above. But, taking that into consideration, there does not appear to be a link between cancer relapse and pregnancy. You may be told to wait a few years before attempting to conceive just to ensure your overall health and the passage of cancer treatments out of the body.

There are rare cases when cancer treatments cause long-term side effects that involve systemic organs like the lungs and heart. If this is the case, pregnancy could place undue pressure on these organs and cause further impairment or failure. This possibility needs to be addressed before you conceive.

There are also cancer treatments that leave a woman infertile. If this is the case, there are alternatives including surrogacy and adoption. Cryogenics are also an option if you choose to freeze your eggs before cancer treatment. Even if you have no viable eggs left, the frozen eggs can be fertilized and implanted.

Key Take-Aways

  • Dealing with cancer during a pregnancy is uncommon.
  • There are safe cancer treatments that can be used during pregnancy, but some are unsafe and may harm the fetus.
  • There are benefits and risks to all cancer treatments – talk with your doctor about both.