Breast cancer is the most common cancer and the leading cause of mortality among Brazilian women. Once the tumor is detected, prompt treatment is essential to improve prognosis and reduce both the physical and psychological suffering of the patient and her family. However, access to oncology treatment varies across regions, with disparities remaining significant. Primary health care holds great potential for promoting breast cancer screening and early detection. However, the impact of primary care networks on access to treatment is still underexplored. This study examines the effect of primary health care team availability on breast cancer notification rates and the average waiting time for surgical treatment in Brazilian municipalities, using a panel of public health indicators from 2015 to 2023. The results indicate that, while waiting times have decreased across all regions, inequalities persist, especially in the North. Specifically, increasing the availability of primary health care teams leads to higher breast cancer notification rates in the North, Northeast, and Center-West regions, and reduces surgical waiting times in the Northeast and South. These findings underscore regional health disparities and the critical role of primary care in ensuring timely diagnosis and treatment of breast cancer.