What Happens to a BCC Left Unremoved?

Basal cell carcinoma is a very slow growing malignancy. It's mode of progression is mostly by local destruction of the tissue. This usually happens over a very long period of time (months to even years). There are multiple subtypes of this cancer and the more agressive types can grow faster and even metastasis to lymph nodes in rare cases.

Thus, even though this is not the type of cancer to usually shorten the patient's lifespan, if neglected, particularly in sensitive areas such as facial structures, it can cause significant morbidly or deformity.

Basal cell carcinomas are very slow growing malignancies but if left untreated they can cause bleeding, ulceration and invasion. In some cases they can rarely metastasize.  Never leave a basal cell carcinoma untreated as they become a much bigger problem if you don't treat them early.  Neglecting a basal cell carcinoma is a bad idea.  Please see an expert dermatologist - Mohs surgery is the gold standard for certain types of basal cell carcinomas.  I hope this helps.

It is rare for someone to die from non-melanoma skin cancers.  Nonetheless they can be aggressive.  If left untreated basal cell cancers can erode deep into cartilage and bone and are very locally destructive.  squamous cell cancers can be more aggressive and sometimes can metastasize to local lymph nodes.  It is best to treat these as soon as they are diagnosed.

You would be hard pressed to meet many physicians who would entertain or advocate leaving a diagnosed basal cell cancer alone. Best.Dr. Karamanoukian 

As others have already mentioned, BCCA is generally slow growing and indolent.  However, if given long enough, a basal cell carcinoma on the face will spread locally and can eventually affect nerves and even the brain.  Patients with chronic immunosuppression, such as with chronic lymphocytic leukemia (CLL), develop much more aggressive variants.  Given the cumulative solar exposure in SW Florida and an aging patient population, I have seen a number of patients with CLL and squamous/ basal cell carcinoma die from skin cancers.  If you have an SCCA/BCCA, it should be surgically removed within a reasonable time frame of diagnosis.