Breast cancer in pregnant women

DEFINITION: Gestational breast cancer is defined as breast cancer that occurs during pregnancy or up to one year thereafter.

ALSO KNOWN AS: Gestational breast cancer, lactational breast cancer, postpartum breast cancer

RELATED CONDITIONS: Lactating adenoma, fibroadenoma, cystic disease, lobular hyperplasia, milk retention cyst (galactocele), abscess, lipoma, hamartoma, leukemia, lymphoma, sarcoma, neuroma, tuberculosis

Risk factors: It is generally believed that breast cancer is years in the making. Thus, pregnancy can be an aggravating for breast cancer because the physiologic changes that occur in the breast during pregnancy may mask an occult or nonpalpable mass. There may also be denial on the part of the physician or patient that breast cancer can occur during pregnancy, further aggravating the underlying risk. Moreover, the elevated levels of estrogen (hundredfold increase) and progesterone (thousandfold increase) during pregnancy may also stimulate cancer growth. Other traditional risk factors for breast cancer include a history of breast disease, menarche (onset of menstrual activity) before the age of twelve, drinking three or more alcohol-containing drinks daily, increased bone density, a sedentary lifestyle, nulliparity (no previous live births), first birth after the age of thirty, a first-degree relative (mother or sister) with breast cancer, upper socioeconomic status, a history of endometrial or ovarian cancer, chest irradiation, increased breast density, a history of breast cancer, dietary fat intake (especially saturated fat), and obesity.

Etiology and the disease process: Like all cancers, breast cancer arises when an oncogene (cancer-causing gene) is activated or the tumor-suppressor gene controlling the oncogene is silenced. Regardless of the precipitating risk factor, breast cancer appears to reflect the cumulative exposure to estrogen and progesterone.

Incidence: Based on several analyses, the actual incidence of breast cancer during pregnancy is estimated at one in three thousand pregnancies, as reported by the National Cancer Institute (NCI) in 2023. The NCI and American Cancer Society (ACS) further report that breast cancer during pregnancy is the most common malignancy occurring during and immediately after pregnancy. Of concern is that the incidence will most likely increase as women delay childbearing since women who have their first term pregnancy after the age of thirty-five have a higher risk of breast cancer compared with women who have their first term pregnancy before the age of twenty, as noted by the Susan G. Komen Foundation.

Symptoms: Most often, women with breast cancer during pregnancy complain of a painless mass in the breast or a nipple discharge; a bloody nipple discharge is particularly concerning.

Screening and diagnosis: All pregnant women should undergo a complete physical examination at the time they register for prenatal care, including a thorough breast examination. All new breast masses or nipple discharges should be evaluated promptly and not delayed until the pregnancy has been completed. The NCI stated that as of 2023, the mean age at diagnosis of breast cancer during pregnancy is thirty-two to thirty-eight years. In most cases, the disease is advanced at the time of diagnosis. In general, the number of positive is greater, the tumors are larger, the steroid hormone status is more often negative, the number of cells synthesizing DNA is greater, the number of mutations involving BRCA1 and BRCA2 is greater, and the tumor suppressor p53 is more often down-regulated. Although the usefulness of mammography has been questioned in women younger than forty years of age because of higher breast density, mammography during pregnancy (in which breast density is increased) has been shown to be between 74 and 100 percent sensitive in detecting malignancies. The exposure to the fetus is negligible and should not be a deterrent. Ultrasound, which carries no fetal irradiation risk, has been shown to be 100 percent sensitive in detecting a malignancy when the breast mass is palpable. However, the diagnosis rests with pathologic confirmation, which can be obtained with a fine needle biopsy, a core needle biopsy, or an excisional biopsy. Staging is performed to determine if metastasis has occurred.

Treatment and therapy: The management of breast cancer during pregnancy has the same goal as in patients who are not pregnant. Termination of pregnancy is not indicated. Surgery is generally delayed until the second trimester, and for nonmetastatic diseases, a or simple mastectomy is considered the standard conservative procedure. Similarly, even though all chemotherapeutic agents are category D (teratogenic), they have accumulated a favorable safety profile when used in the second and third trimesters. Fetal malformations range from 14 to 19 percent in the first trimester to 1.3 percent in the second and third trimesters based on pregnant women treated with 5-fluorouracil, doxorubicin, and cyclophosphamide (a standard chemotherapeutic regimen). Breast-conserving surgery may be performed, but the need for follow-up radiation and/or chemotherapy treatments may preclude this option for women who are diagnosed early in pregnancy.

Prognosis, prevention, and outcomes: Women who are diagnosed with breast cancer during pregnancy are often diagnosed at a later stage because breast changes during pregnancy, including increased breast size and changes in breast texture, make small, early-stage tumors harder to detect and diagnose. New cases in pregnant women are typically found five to fifteen months after symptoms started, which is why the cancer is often late stage (III or IV). The ACS reports that the five-year survival rate for pregnant women with early-stage breast cancer has been shown to be comparable to that of nonpregnant women. However, for late-stage cancer, after metastasis, the five-year survival rate is only 10 percent, according to the NCI. Whether pregnancy itself is an independent factor for poorer prognosis remains subject to investigation.

Bibliography

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