Breast cancer

Overview for patients

Breast cancer is a malignant tumour that starts in the cells of the breast. The most common type of breast cancer is ductal carcinoma, which begins in the cells that line the ducts or tubes that carry milk from the glands to the nipple. Breast cancer can also begin in the cells of the lobules and in other tissues in the breast. Invasive breast cancer is breast cancer that has spread from where it began in the ducts or lobules to surrounding tissue.

For women in Ontario, breast cancer is the most frequently diagnosed type of cancer. 

Below are a list of resources to help you stay informed and answer any questions you may have at each stage of your cancer journey.

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