> Could slightly increased sun exposure on one's left arm and result in increased cancers elsewhere on one's left side? I'm no doctor, but I wondered if metast

> Could slightly increased sun exposure on one's left arm and result in increased cancers elsewhere on one's left side? I'm no doctor, but I wondered if metastasis via the lymphatic system might be a possible explanation. From my utterly cursory search, I get the impression that the lymphatic network is a common route of metastasis, but while it might spread melanoma from the arm to the trunk (and perhaps preferentially to the same side), it seems to go the wrong way to be the vector from there to the hips and thighs. There's also the question of whether a melanoma that has spread to the lymph nodes is still counted as an instance of melanoma, and the most I can say about that is that one paper I skimmed seemed to be using the term in that manner. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7729077/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7729077/