Chemotherapy for basal cell carcinoma is topical, meaning the chemicals are applied directly to the tumor.  It is also sometimes used for squamous cell carcinoma.

Topical Therapies

 Imiquimod

Imiquimod was recently approved by the Food and Drug Administration (FDA) as a treatment for superficial BCCs most often found on the trunk, neck and arms and legs. Trials are underway for treatment of other types of BCC. The cure rate has been shown to range from 75 to 90 percent. It is an immune response modifier which stimulates your immune system to attack tumor cells.  When applied as directed, it has been shown in studies to be effective in curing basal cell carcinoma and actinic keratoses.  Imiquimod is rubbed gently into the tumor five times a week for six weeks. Side effects include redness and irritation.  Some patients may experience lymph node enlargement.

5-fluorouracil (5-FU)

The FDA has also approved 5-FU for the treatment of actinic keratoses and superficial BCCs, and it has proved to be effective.

Technique:
The 5% liquid or ointment form of the chemical is gently rubbed into the tumor twice a day for three to six weeks. Pain, itching, and inflammation are quite variable from person to person. Some patients do not experience any discomfort, while others have pain and discontinue treatment (this may be an allergic response). 5-FU seems to have little or no effect on normal skin, attacking only the diseased tissues. Redness and irritation are common and on rare occasions side effects can be severe. Patients who have been treated with 5-FU are advised to stay out of the sun because ultraviolet light seems to encourage or enhance severe response.

Advantages of Topical Agents:
These medications are good, effective options for patients with multiple basal cell carcinomas or for poor surgical candidates (elderly patients, those taking blood thinners, or having systemic disease). They also give a good cosmetic result, as the tissue is never cut.

Disadvantages:
Because the course of therapy is longer, it will take time for the cancer to clear. This leaves some patients with a sense of anxiety because there is not an immediate resolution. The efficacy rate is lower than for other treatments, leaving some patients with the need for a second round of topical therapy, or perhaps with a different type of treatment modality. Imiquimod cannot be used in patients who are immunocompromised, as the immune response is essential.

Recommendations: 
The tendency of these growths to recur is greater after topical treatment than after a more aggressive approach. Yet the treatment is simple and the cosmetic benefit is great (there is less scarring) so that in some cases both patient and doctor are willing to repeat the treatment periodically rather than resort to surgery, even if the cure by surgery is more likely to be complete.