Is basal cell carcinoma serious?

Yes and no: Basal cell carcinoma is a type of skin cancer which is not malignant in the sense it will not spread to distant parts of the body and threaten life the way that other cancers can. It is still a cancer though and since it tends to affect the face it can grow into cosmetically sensitive areas and near nerves. It sometimes needs more complicated surgery to remove given the location on the face.

Not usually: Basal cell cancers can be locally aggressive and depending on the location a challenge to remove requiring extensive surgery, but they rarely spread to other organs and are usually small and excised under local anesthetic.

Not usually: Most basal cell carcinomas are small, grow rapidly, and rarely spread to other parts of the body. They are best treated (and easily treated) when small. If allowed to continue to grow, treatment can be more difficult and disfiguring.

Can become serious: Basal cell cancer is the most common type of skin cancer. When treated early and while it is still small, the cure rates with simple surgery are excellent. If neglected, basal cell carcinomas can become very destructive and much more difficult to treat and reconstruct.

No: Basal cell is a locally agressive cancer that typically can not spread (metastasize). Therefore if removed it is gone. I have seen them the size of a baseball and they can grow into surrounding tissue as well (such as bone or muscle if u let it go for years) so it is something that should be take care of sooner than later.