Because cancer tends to be life threatening and because delays in treatment may reduce the likelihood of successful treatment, cancer is often treated the same way whether the woman is pregnant or not. Some of the usual treatments (surgery, chemotherapy, and radiation therapy) may harm the fetus. Thus, some women may consider pregnancy termination. However, treatments can sometimes be timed so that risk to the fetus is reduced.
In some cancers (such as rectal and gynecologic cancers Overview of Female Reproductive System Cancers Cancers can occur in any part of the female reproductive system—the vulva, vagina, cervix, uterus, fallopian tubes, or ovaries. These cancers are called gynecologic cancers. The most common... read more ), treatment may be modified during pregnancy.
Diagnosis and management of cancer during pregnancy or the period after pregnancy (postpartum period) require a multidisciplinary team including oncologists and high-risk obstetrics specialists.
Rectal cancer
Rectal cancer Colorectal Cancer Family history and some dietary factors (low fiber, high fat) increase a person’s risk of colorectal cancer. Typical symptoms include bleeding during a bowel movement, fatigue, and weakness... read more 
may require removal of the uterus (hysterectomy) to be sure that all the cancer is removed. In such cases, cesarean delivery may be done as early as 28 weeks of pregnancy so that hysterectomy can be done and aggressive cancer treatment can be started.
Cervical cancer
Pregnancy does not appear to worsen the prognosis of cervical cancer Cervical Cancer Cervical cancer develops in the cervix (the lower part of the uterus). Most cervical cancers are caused by human papillomavirus (HPV) infection. Cervical cancer usually results from infection... read more 
.
If pregnant women have an abnormal Papanicolaou (Pap) test, doctors examine the cervix with a binocular magnifying lens (colposcopy Colposcopy Sometimes doctors recommend screening tests, which are tests that are done to look for disorders in people who have no symptoms. If women have symptoms related to the reproductive system (gynecologic... read more 
). Colposcopy does not harm the fetus or affect the pregnancy. Doctors usually consult an expert when doing the colposcopy to help them determine whether they should take a sample of any abnormal tissue to be examined under a microscope (biopsy Cervix or vagina Sometimes doctors recommend screening tests, which are tests that are done to look for disorders in people who have no symptoms. If women have symptoms related to the reproductive system (gynecologic... read more ). A cervical biopsy is not routinely done in pregnant women because bleeding and preterm labor are risks.
If cervical cancer is in a very early stage, treatment is usually postponed until after delivery.
If more advanced cervical cancer is detected early in pregnancy, it is usually treated immediately as needed.
If it is diagnosed late in pregnancy, doctors explain the risk of postponing treatment so that women can decide whether to postpone treatment until after the fetus is mature enough to be delivered. However, if cancer is advanced, cesarean delivery is done, followed by hysterectomy.
Other gynecologic cancers
Ovarian, fallopian tube, and peritoneal cancers Ovarian Cancer, Fallopian Tube Cancer, and Peritoneal Cancer Ovarian cancer is cancer of the ovaries. It is related to fallopian tube cancer, which develops in the tubes that lead from the ovaries to the uterus, and peritoneal cancer, which is cancer... read more are hard to detect after 12 weeks of pregnancy, because the uterus rises out of the pelvis, making detecting the cancers more difficult.
If advanced, ovarian cancer during pregnancy may be fatal before completion of the pregnancy. Affected women require removal of both ovaries as soon as possible.
Breast cancer
Breast cancer Breast Cancer Breast cancer occurs when cells in the breast become abnormal and divide into more cells uncontrollably. Breast cancer usually starts in the glands that produce milk (lobules) or the tubes ... read more 
is hard to detect during pregnancy because the breasts enlarge. If any lump is detected, doctors evaluate it.
Usually, breast cancer should be treated immediately.
Leukemia and Hodgkin lymphoma
Leukemia Leukemias and Hodgkin lymphoma Hodgkin Lymphoma Hodgkin lymphoma is a cancer of a type of white blood cell called lymphocytes and is distinguished from other lymphomas by the presence of a particular kind of cancer cell called a Reed-Sternberg... read more are uncommon during pregnancy. The anticancer medications typically used to treat these cancers increase the risk of miscarriage and birth defects.
Because leukemias can become fatal rapidly, women are treated as soon as possible, without waiting to allow the fetus to mature.
If Hodgkin lymphoma is present only in areas above the diaphragm (the muscle that separates the chest from the abdomen), radiation therapy may be used, and the abdomen is shielded to protect the fetus from radiation. If lymphoma is present in areas below the diaphragm, doctors may recommend abortion.
