By Dr Joe Kabyemela, MD
Cancer. The dreaded word.
Pregnant women are inevitably in their youth or occasionally in their early middle age. This means that they are at risk of those cancers that affect people in this age range. Cancer of the cervix, ovary, breast, blood (leukaemia), skin (melanoma) and lymphatic system (lymphoma) come to mind. While it is true that most of these are commoner in late middle age and beyond, they are also seen in the younger reproductive age groups. This is why roughly one in a thousand pregnant women will be found to have cancer.
This obviously raises very serious questions. Is it treatable? Is the treatment compatible with continuing pregnancy? Will it affect the baby? Should a termination be performed and is this an acceptable proposition? ...and many more.
Cancers are a very diverse group and no short overall summaries are possible. For some, such as cervical cancer, treatment is required almost promptly or at the very least within a few short weeks of diagnosis to maximize the chances of a favourable outcome. Nor is treatment compatible with continuing pregnancy and very rarely with future pregnancy. These facts are discussed in detail here.
Other forms of cancer treatment - such as that of the breast or thyroid - may be compatible with continuing pregnancy, depending on the stage of the disease and the pregnancy itself. Again, all these facts are tackled here. There are never any cut and dried answers with cancer, let alone where pregnancy adds another dimension to the equation.
Does pregnancy increase the possibility of developing cancer?
No. A woman's risk of developing any of the various forms of cancer remains the same when pregnant.
If a woman develops cancer during pregnancy, will the fetus be affected?
Not directly. The action that is likely to be taken to treat the condition is more likely to have an adverse effect on the fetus than the actual cancer. It depends on the type of cancer, the form of treatment adopted and the stage of pregnancy.
Can the cancer spread to the fetus?
This is exceedingly rare. Only a handful of cases have ever been reported in the world. The working assumption is always that this is not going to happen.
How will cancer diagnosed in pregnancy be treated?
Again, this depends on the type of cancer, the stage of the disease and occasionally the patient's wishes, as we shall see below. If the treatment of choice is radiotherapy, especially in the first half of pregnancy, the fetus is very unlikely to survive; even less so if the cancer is in the pelvic cavity or abdomen.
If chemotherapy is the chosen treatment, this is usually safe for the fetus, provided that the pregnancy has gone past the crucial first twelve weeks during which the fetus's body organs are formed. However, this does not apply to all types of chemotherapy.
Chemotherapy used in the last 25 weeks of pregnancy is unlikely to cause developmental fetal abnormalities. If surgery is the treatment of choice, the fetus is usually safe, provided the operation is not on the womb itself.
Does pregnancy make cancer grow faster or more aggressively?
Only one type of cancer - malignant melanoma - has ever been reported to show features of increased aggressiveness during pregnancy. Malignant melanoma is a relatively rare form of skin cancer but there is steadily increasing incidence in the last few years. This is particularly important among young women in their late teens and twenties where the use of sunbeds has exploded. Malignant melanoma can also arise in the eye. Other forms of cancer behave the same during pregnancy as they do in a non-pregnant state.