Any excessive enlargement of the abdomen or the appearance of pressure symptoms should always lead one to make a careful examination, and in not a few cases a tumour will be found occupying the pelvic cavity. In rare instances malignant tumours of the rectum may so obstruct the pelvic canal as to render caesarean section imperative.
—J. Whitridge Williams (1903)
Any neoplasm can complicate pregnancy, and as written by Williams, physical examination often suggests the diagnosis. Current imaging also allows a greater number of these to be identified antepartum. Most encountered neoplasms are benign, and uterine leiomyomas and ovarian cysts are the most frequent.
Cancer has an incidence approximating 1 per 1000 pregnancies (Parazzini, 2017; Salani, 2014). One third are diagnosed prenatally, and the others within 12 months of delivery. Some of the more frequent ones are shown in Figure 63-1. Breast cancer is found in 1 in 5000 pregnancies, thyroid—1 in 7000, and cervical—1 in 8500 (Smith, 2003). These, along with lymphoma and melanoma, account for 65 percent of malignancy cases in pregnancy (Eibye, 2013). For some cancers—ovary, endometrium, and breast—evidence suggests that high parity is protective (Högnäs, 2014).
Proportion of malignancies during pregnancy and within 12 months of delivery in 4.85 million women from the California Cancer Registry. GI = gastrointestinal. (Data from Smith, 2003.)
During pregnancy, cancer management poses unique problems related to fetal concerns, and treatment must be individualized. Considerations include the type and stage of malignancy, the desire for pregnancy continuation, and inherent risks associated with modifying or delaying cancer treatment.
CANCER THERAPY IN PREGNANCY
Operative procedures indicated for cancer include those for diagnosis, staging, or therapy. Fortunately, most procedures that do not interfere with the reproductive tract are well tolerated by both mother and fetus (Chap. 46). Although many operations have classically been deferred until after 12 to 14 weeks’ gestation to minimize miscarriage risks, this probably is not necessary. We are of the opinion that surgery should be performed regardless of gestational age if maternal well-being is imperiled.
Both pregnancy and malignancy are risk factors for venous thromboembolism (VTE). In one study, Bleau and coworkers (2016) reported a higher risk of VTE in gravidas with myeloid leukemia, Hodgkin disease, cervical cancer, and ovarian cancer compared with that in pregnant women without a malignancy. The risk was not increased in those with brain or thyroid cancer, melanoma, or lymphoid leukemia. That said, current guidelines lack specific recommendations for pregnant women undergoing surgeries for cancer. Thus, depending on the complexity of the planned procedure, it seems reasonable to use prophylactic low-molecular-weight heparin combined with elastic stockings and/or intermittent pneumatic compression as described in Chapter 52.