One of the well-known websites where you can find cancer-related medical image datasets is The Cancer Imaging Archive (TCIA). TCIA is a publicly accessible repository providing a vast collection of medical imaging data, including various cancer-related images. It offers datasets from research studies, clinical trials, and imaging modalities.
You can visit the TCIA website at https://www.cancerimagingarchive.net/ to explore the available datasets. The website provides search functionalities, allowing you to filter datasets based on cancer type, imaging modality, patient demographics, and more. You can access and download the data after creating a free account on the TCIA platform.