Is there any chance that a swollen lip could be related to cancer? my husband had testicular cancer that metastasized to the lungs about ten years ago

Maybe: More commonly the swollen lip can be secondary to a medication he is taking, e.g. Some antihypertensives can cause skin swelling. But, a rare complication of cancer can also cause an acquired angioedema. There are blood tests to identify it. Consult your doctor.

Not common: While metastatic cancer can cause all sorts of strange symptoms, a swollen lip is far more likely to be due to a much more benign and less serious problem. In addition to trauma( like biting your lip or bumping it), allergic reactions, viral caused cold sores, sun irritation, dryness, or infections would b uh more common than a cancer.