Triple-negative breast cancer (TNBC) is a distinct type of breast cancer, characterized by the absence of three specific receptors: estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor receptor 2 (HER2). Because TNBC cells do not rely on these common pathways for growth, standard hormone therapies and HER2-targeted drugs are ineffective. This article provides statistics on TNBC’s prevalence, patient demographics, treatment outcomes, and how it differs from other breast cancer types.
Incidence and Demographics
Triple-negative breast cancer accounts for approximately 10% to 15% of all breast cancer cases. While breast cancer risk generally increases with age, TNBC is observed more frequently in younger women, particularly those under 40. In the United States, notable racial and ethnic disparities exist in its incidence.
Black women have the highest incidence rates of TNBC, at 25.2 per 100,000 women, significantly higher than White women at 12.9 per 100,000. This disparity is pronounced in non-Hispanic Black women, where about 21% of breast cancers are triple-negative, double the rate seen in other racial and ethnic groups. Hispanic and American Indian or Alaska Native women have similar incidence rates of approximately 11.1-11.2 per 100,000, while Asian or Pacific Islander women have the lowest rates at 9.0 per 100,000. Geographic variations are also observed, with some states showing higher rates among Black women, such as Delaware, Missouri, Louisiana, and Mississippi.
Survival Rates and Prognosis
The prognosis for triple-negative breast cancer is less favorable compared to other breast cancer types, due to its aggressive nature and fewer targeted treatment options. The overall 5-year relative survival rate for TNBC across all stages is approximately 77%. This means individuals with TNBC are about 77% as likely as those without the cancer to live for at least five years after diagnosis.
Survival rates vary depending on the stage at diagnosis. For localized TNBC, where cancer has not spread beyond the breast, the 5-year relative survival rate is around 91%. If cancer has spread to nearby structures or lymph nodes (regional stage), the 5-year survival rate drops to about 65%. When TNBC has spread to distant parts of the body, such as the lungs, liver, or bones (distant or metastatic stage), the 5-year survival rate is around 12%. Factors influencing prognosis include age, with studies suggesting higher survival rates in older individuals, and response to initial treatments like chemotherapy.
Recurrence Patterns
Triple-negative breast cancer has a higher propensity for recurrence compared to other breast cancer subtypes. Approximately 40% of individuals with stage 1 to stage 3 TNBC may experience recurrence after standard treatment. This recurrence most often occurs early in the post-treatment period, within the first 3 to 5 years following initial diagnosis.
The risk of recurrence is highest during the first three years, decreasing sharply after five years of being disease-free. Common sites for recurrence include distant metastases, with the lungs, brain, and liver frequently affected. Studies show brain recurrence in about 15-30% of cases, lungs in 14-55.9%, liver in 8-22.8%, and bones in 11-36.8% of cases.
Statistical Differences from Other Breast Cancers
Triple-negative breast cancer presents distinct statistical profiles compared to other breast cancer subtypes, such as hormone receptor-positive (HR+) and HER2-positive (HER2+) breast cancers. While TNBC accounts for 10-15% of all breast cancers, HR+ cancers are the most common, making up about 60-70% of cases. TNBC affects younger women and has a higher grade, indicating faster growth and spread.
Survival rates also differ significantly. The overall 5-year survival rate for TNBC is 8-16% lower than that of HR+ breast cancer. For localized disease, the 5-year survival rate for TNBC is 91%, compared to 99% for all breast cancers combined. Regarding recurrence, TNBC has a higher risk of early recurrence, often within the first 3-5 years, while HR+ cancers can have late recurrences even beyond 10 years. These differences arise because TNBC lacks the specific receptors that allow for targeted therapies, such as hormone therapy for HR+ cancers or HER2-targeted drugs for HER2+ cancers, making chemotherapy the primary systemic treatment option.