Papillary breast cancer is a less common form of breast cancer. This article explains its characteristics, how it is staged, and typical treatment approaches.
Understanding Papillary Breast Cancer
Papillary breast cancer is a rare type of breast cancer distinguished by finger-like projections (papillae). These growths typically originate within the milk ducts of the breast. It accounts for approximately 0.5% to 1% of all breast cancer diagnoses.
This cancer can present in two main forms: pure papillary carcinoma and invasive papillary carcinoma. Pure papillary carcinoma is a type of ductal carcinoma in situ (DCIS), where cancer cells are confined to the milk ducts. In contrast, invasive papillary carcinoma signifies that the cancer cells have moved beyond the ductal walls into the adjacent breast tissue.
The distinction between these forms is important for treatment, as their potential for spread differs. Papillary tumors often possess well-defined borders and tend to be smaller in size compared to other breast cancer types.
Principles of Breast Cancer Staging
The staging of breast cancer provides a standardized way to describe the extent of the disease, guiding treatment decisions and offering insights into prognosis. The most widely used system is the TNM (Tumor, Node, Metastasis) system. This system evaluates three key components of the cancer.
The “T” component describes the size and local extent of the primary tumor within the breast. Categories range from T0 (no evidence of primary tumor) to Tis (carcinoma in situ, indicating non-invasive cancer) and T1 through T4, which denote increasing tumor size or spread to surrounding tissues like the chest wall or skin. The “N” component indicates whether cancer cells have spread to nearby lymph nodes, particularly those in the armpit (axillary lymph nodes). N0 means no regional lymph node involvement, while N1 to N3 signify increasing numbers and locations of affected lymph nodes.
The “M” component addresses whether the cancer has metastasized, meaning it has spread to distant parts of the body beyond the breast and regional lymph nodes. M0 indicates no distant spread, while M1 signifies that the cancer has spread to distant organs such as the lungs, liver, or bones. These TNM classifications are combined with other factors, such as tumor grade and biomarker status, to assign an overall stage, typically ranging from Stage 0 to Stage IV. Lower stages indicate more localized disease, while higher stages suggest more extensive spread.
Staging of Papillary Breast Cancer
Papillary breast cancer is frequently diagnosed at an early stage, often as non-invasive or early-stage invasive disease. Many cases are classified as Stage 0, referring to papillary ductal carcinoma in situ (DCIS).
When it is invasive, papillary breast cancer commonly presents as Stage I. This stage typically involves a small tumor (T1) that has not spread to nearby lymph nodes (N0) or distant sites (M0).
Lymph node involvement, a significant factor in breast cancer staging, is less common with papillary breast cancer compared to other invasive breast cancer types. While papillary breast cancer can progress to higher stages if it spreads to lymph nodes or distant organs, its typical presentation at lower stages contributes to its generally favorable nature. Most individuals diagnosed with this type of cancer are found to have either Stage I or Stage II disease.
Prognosis and Treatment Approaches
Given its common diagnosis at early stages, papillary breast cancer generally carries a favorable prognosis.
Treatment for early-stage papillary breast cancer primarily involves surgery to remove the cancerous tissue. This may include a lumpectomy, which preserves most of the breast while removing the tumor and a margin of healthy tissue, or a mastectomy, involving the removal of the entire breast. The choice of surgical procedure often depends on the tumor’s characteristics.
Following surgery, radiation therapy may be recommended, particularly after a lumpectomy, to reduce the risk of recurrence in the breast. Systemic therapies, such as chemotherapy, are less frequently used for non-invasive or very early-stage invasive papillary breast cancer. Chemotherapy is typically reserved for cases where the cancer has spread to the lymph nodes. Hormone therapy may be prescribed if the cancer cells are found to be hormone receptor-positive, which is common in papillary breast cancer, as this treatment can block hormones that fuel cancer growth. Papillary cancers are less likely to be HER2-positive, meaning that HER2-targeted therapies are generally not indicated.