The influence of surgical procedure and the effect of chemotherapy on nodal and distant metastases of human malignant melanomas that have been grafted into nude mice.

Malignant melanoma of the oral mucosa is common in Japan. The effects on metastasis of puncturing the tumor before surgery or using chemotherapy after extirpation of the tumor were studied using animal models. G-361 cells were transplanted subcutaneously into mice. In half the animals, the subcutaneous tumor was punctured with an 18G needle twice a week from 2 weeks after transplantation until death. In the other mice, the subcutaneous tumor was extirpated 6 weeks after transplantation; the animals were killed 2 weeks later. Dimethyl triazeno imidazole carboxamide (DTIC) or cisplatin (CDDP) were injected into the peritoneal cavity 3 days before extirpation or during extirpation. Metastases to the axilla lymph node and the lung were examined in both groups. The animals that received puncturing developed lymph node and pulmonary metastasis earlier and more frequently than those without puncturing. 50% of mice that received no anticancer agent, had lymph node and pulmonary metastases after tumor extirpation. Preoperative DTIC or CDDP reduced the frequency of metastasis to 25-35%. DTIC or CDDP administration during extirpation, significantly reduced the metastasis rate to 7-10%. Prognosis for oral melanoma patients may be better when surgery and postoperative chemotherapy are performed simultaneously without preoperative surgical procedures.