Breast cancer diagnosed during pregnancy or within the first year after childbirth represents a particularly complex situation, both medically and emotionally. Although it is considered a rare condition, its incidence has increased in recent decades, largely due to the growing trend of delayed motherhood. As more women become pregnant at later ages, the likelihood of pregnancy coinciding with breast cancer rises, making this condition an increasingly relevant challenge in modern clinical practice.

A review conducted by Dequanter and colleagues, based on the analysis of multiple scientific studies, provides a comprehensive overview of the clinical presentation, diagnostic approaches, therapeutic options, and prognosis of pregnancy-associated breast cancer.

It is estimated that breast cancer related to pregnancy accounts for between 0.2% and 3.8% of all breast cancer cases, corresponding to approximately one to three cases per 10,000 pregnancies. While these numbers may appear low, the clinical significance of this condition is considerable, as it is often diagnosed at more advanced stages. This is associated with a higher likelihood of axillary lymph node involvement, which directly affects maternal prognosis and may pose additional risks to the fetus. Most patients are between 31 and 36 years of age, a range that coincides with later reproductive years.

One of the main challenges of breast cancer during pregnancy is delayed diagnosis. The normal physiological changes that occur in the breast during gestation—such as enlargement, increased vascularity, and tissue congestion—can make tumor detection more difficult. In addition, both patients and healthcare professionals may attribute breast lumps or discomfort to normal pregnancy-related changes, delaying clinical evaluation. This diagnostic delay, which in some cases may extend for several months, is often associated with larger tumors and a higher probability of lymph node metastasis at the time of diagnosis.

From a clinical perspective, any persistent breast mass, skin changes, unilateral bloody nipple discharge, or axillary lymphadenopathy should prompt immediate evaluation, even during pregnancy. The challenge lies not only in identifying the lesion, but also in selecting appropriate diagnostic tools that allow confirmation of the diagnosis without compromising fetal safety.

In this context, breast ultrasound has become the first-line imaging modality due to its high sensitivity and absence of ionizing radiation. Mammography, although historically controversial during pregnancy, can be performed with appropriate abdominal shielding, as the radiation dose reaching the fetus is minimal. However, its diagnostic utility may be limited by the increased density of gestational breast tissue. In many cases, definitive diagnosis requires a surgical biopsy, as cytological evaluation may be difficult to interpret due to pregnancy-related cellular changes.

From a histopathological standpoint, breast tumors diagnosed during pregnancy do not differ significantly from those observed outside this period. Infiltrating ductal carcinoma is the most common subtype, and general histological features are comparable. Nevertheless, some studies suggest a higher frequency of inflammatory forms during pregnancy, which may partly explain the more aggressive clinical presentation observed in certain patients.

Axillary lymph node involvement is one of the most important prognostic factors in pregnancy-associated breast cancer. Reported rates of nodal involvement range from 50% to 80%, higher than those observed in non-pregnant women of similar age. This increased frequency appears to be primarily related to diagnostic delay rather than a direct effect of pregnancy on tumor biology.

Figure 1. Breast cancer during pregnancy is challenging due to overlapping physiological changes, limited diagnostic options, and the need for carefully individualized treatment to protect both mother and fetus.

 

The treatment of breast cancer during pregnancy requires a careful balance between adequate maternal cancer control and fetal protection. Therapeutic management must be individualized, taking into account the stage of the disease, gestational age, and the patient’s preferences. Surgery is the cornerstone of treatment and can be safely performed during any trimester of pregnancy. Mastectomy with axillary dissection remains the standard approach, although breast-conserving surgery may be considered in selected cases, provided that radiotherapy can be safely postponed until after delivery.

Radiotherapy during pregnancy poses significant risks to the fetus, particularly during the first trimester, when organ development is most vulnerable to ionizing radiation. For this reason, it is generally deferred until after childbirth. Chemotherapy, on the other hand, is contraindicated during the first trimester due to the high risk of teratogenic effects. However, in the second and third trimesters, it may be administered in selected cases with a relatively acceptable safety profile, although risks such as intrauterine growth restriction or preterm delivery remain.

The role of hormone therapy during pregnancy is limited and insufficiently studied. Furthermore, the elevated hormone levels characteristic of pregnancy may interfere with the interpretation of hormone receptor status, complicating treatment decisions based solely on these markers.

In terms of prognosis, pregnancy-associated breast cancer is often associated with lower overall survival compared with breast cancer diagnosed outside of pregnancy. However, when outcomes are adjusted for tumor stage and lymph node involvement, these prognostic differences are substantially reduced. This supports the notion that the poorer prognosis is primarily related to delayed diagnosis and greater tumor burden at presentation, rather than pregnancy itself.

In conclusion, breast cancer during pregnancy is a complex clinical entity that involves diagnostic, therapeutic, and ethical challenges. Early detection, multidisciplinary management, and individualized treatment strategies are essential to improve outcomes for both mother and fetus. As delayed motherhood becomes increasingly common, raising awareness of this condition and enhancing healthcare professional training will be crucial to reducing diagnostic delays and optimizing patient care.

 

Main reference:

Dequanter, D., Hertens, D., Veys, I., & Nogaret, J. M. (2001). Mise au point: cancer du sein et grossesse. Revue de la littérature [Breast cancer and pregnancy. Review of the literature]. Gynecologie, obstetrique & fertilite, 29(1), 9–14. https://doi.org/10.1016/s1297-9589(00)00048-5

 

Other reference:

Boere, I., Lok, C., Poortmans, P., Koppert, L., Painter, R., Vd Heuvel-Eibrink, M. M., & Amant, F. (2022). Breast cancer during pregnancy: epidemiology, phenotypes, presentation during pregnancy and therapeutic modalities. Best practice & research. Clinical obstetrics & gynaecology, 82, 46–59. https://doi.org/10.1016/j.bpobgyn.2022.05.001 

Froehlich, K., Schmidt, A., Heger, J. I., Al-Kawlani, B., Aberl, C. A., Jeschke, U., Loibl, S., & Markert, U. R. (2019). Breast cancer, placenta and pregnancy. European journal of cancer (Oxford, England : 1990), 115, 68–78. https://doi.org/10.1016/j.ejca.2019.03.021 

Rossi, L., Mazzara, C., & Pagani, O. (2019). Diagnosis and Treatment of Breast Cancer in Young Women. Current treatment options in oncology, 20(12), 86. https://doi.org/10.1007/s11864-019-0685-7