Cryosurgery of advanced tumors

Abstract

Tumors of the skin include a wide variety of histologic types. The commonest malignant tumors are basal-cell or squamous-cell carcinomas but melanomas and diverse sarcomas are among the less common tumors which occur in the skin. Malignant neoplasms, if neglected and untreated or if resistant to treatment, can grow in size and present special problems in management because of size or location. Regardless of the histologic type, cryosurgery is capable of producing destruction. Small tumors are generally easy to treat. Advanced tumors present greater problems in treatment. This clinic defines the role of cryosurgery in the management of advanced tumors and describes cryosurgical techniques suitable for such lesions. Cryosurgery has been used for skin cancer for about 90 years, and the first clinical trials demonstrated the success of the method. 1–5 Though the early techniques lacked the equipment available today, the physicians using the techniques in those years clearly described the important factors needed and the effect of freezing on the tissue. Modern cryosurgery is scarcely 25 years old and in this time has shown its usefulness in the treatment of skin cancers. Almost any kind of skin cancer can be treated successfully by cryosurgery. Most skin cancers are small, i.e., less than 2 cm in skin surface diameter and 4–5 mm in thickness. Growth is ordinarily slow, and though differences in biologic behavior are evident between basal-cell and squamous-cell epitheliomas, metastatic spread is not common in either type. 6–11 The cryosurgical techniques used in these small skin cancers are well developed and vary chiefly in the choice of spray or probe techniques or in the use of curettage as a preliminary step to aid in diagnosis and facilitate freezing of the base of the cancer. The overall results have been excellent; they are competitive with other methods of management, such as excision or electrodesiccation, and are described in Chapter 8. Advanced skin tumors, on the other hand, provide a substantial challenge to therapy. This clinic focuses on advanced skin cancers, which may be defined as those causing difficult problems in management due to size, extent or location of disease. As a minimum, advanced cancers are those which are greater than 4 cm in diameter on the surface and are ulcerated into the subdermal tissues. Beyond this minimum, skin cancers may grow to a large size and still remain without distant spread, causing problems because of bulk or invasion of important structures, such as nerves and major blood vessels. The defined size is not a critical value. Even small lesions may invade critical structures, including bone and cartilage, and become advanced in the sense that special problems in treatment exist. Furthermore, some cancers may grow to 4 cm and yet remain superficial, perhaps only 3–4 mm deep. Such cancers must be treated carefully but they are not advanced as the term is used in this clinic. Relatively few skin cancers become advanced today, so that any physician is likely to see only small numbers in clinical practice. Recurrent skin cancers, however, or those persistent after diverse methods of therapy may present difficult problems in therapy, so these too are mentioned in this clinic. Advanced skin cancers, even those recurrent after radiotherapy or excision, may be curable by cryosurgery if the disease is still localized. The reasons cryosurgery might be chosen, in preference to excision or radiotherapy, include fixation of the cancer to underlying bone or patients who are at high-surgical risk due to associated disease. Neglected cancers or those cancers which persist after radiotherapy or excision are usually advanced cancers which present problems in management and cryosurgical techniques may be among the last options in therapy. Some cancers, not necessarily advanced, have special characteristics which present a challenge to the ability to freeze a sufficient volume of tissue to be certain of care. For example, in some types of skin cancers, such as sclerosing or morphea-type basal-cell carcinomas and cancers of the scalp or alae nasae, the results of cryosurgery have not been good as compared with other techniques. 12 These lesions require aggressive freezing in situ because of the difficulty in recognizing the extent of the cancer. Skin cancers with indefinite borders require extra care in treatment, and consideration should be given to selective biopsy of the edges to the healing wound.