Value of postoperative radiotherapy for thyroid cancer.

A series of 405 patients with thyroid cancer treated by surgery with or without postoperative radiotherapy from February 1958 through 1979 is reported. The immediate evaluation of the operation was that it was either incomplete or complete. Incomplete surgery implied that there was (1) possible residual tumor in the operative field, the result of difficult dissection of the tumor off the neighboring organs or tissues, as assessed by the surgeon; (2) multiple (more than five) lymph nodes involved; (3) positive border of the removed lesions; or (4) microscopic evidence of tumor in the operative field. Complete surgery implied through extirpation of cancer grossly and microscopically. In 297 patients who had complete surgery, 238 patients treated by surgery alone had a 5-year survival rate of 92% (218/238), while 59 patients who received postoperative radiotherapy had a 5-year survival rate of 78% (46/59). The optimum dose of postoperative radiotherapy was 50-70 Gy in 5 to 8 weeks, with the spinal dose kept under 40 Gy. Our experience shows that postoperative radiotherapy did not improve the survival of patients who had had complete surgery. Yet, in 108 patients who had incomplete surgery, surgery alone yielded a 5-year survival rate of 33% (19/57), while surgery plus radiotherapy yielded a 5-year survival of 71% (36/51). Our observation shows a remarkable benefit with postoperative radiotherapy in patients who have had incomplete surgery (P less than 0.05). According to pathologic criteria, postoperative radiotherapy was more effective in well-differentiated cancers than in poorly differentiated ones. It was equally effective in untreated as well as recurrent lesions. The prognosis for younger patients was better, but the sex of the patients did not affect prognosis.

The biological effects of photodynamic therapy on normal skin in mice--I. A light microscopic study.

A light microscopic investigation of the biological effects of photodynamic therapy using hematoporphyrin derivative and red light irradiation has been carried out. HpD alone, even used at a dose of 50 mg/kg, did not cause histologically discernible changes. The irradiation alone used in this experiment caused only slight or moderate dilatation and congestion of blood vessels, which disappeared completely within several hours after light exposure. In the PDT treated mouse ears severe degeneration and necrosis of skin tissue occurred within 1-2 days. The importance of adequate drug and light doses and proper interval chosen for obtaining best therapeutic effects and protection of surrounding normal tissues was pointed out. The possible mechanism of the PDT action in vivo was briefly discussed.

The biological effects of photodynamic therapy on normal skin in mice--II. An electron microscopic study.

In the present study it has been demonstrated that the ultrastructural changes in mouse ear skin after PDT action occurred much more distinct and earlier than those observed in the histological study. Various types of cells in the skin respond to the photodynamic action differently. The endothelial cells, fibroblasts and nerve fibers are most sensitive. In contrast, the keratinocytes and chondrocytes often remain rather well preserved after PDT treatment. The possible mechanism of PDT action was briefly discussed.

[Photodynamic therapy (PDT) of bladder cancer in the rat].

PDT of rat bladder cancer, induced by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) was studied. All animals were divided at random into three groups. Group 2 and 3 were treated by hematoporphyrin derivative (HPD)-laser PDT while group 1, without treatment, served as control. The results showed that the malignant lesions could be selectively and obviously destroyed, if the whole tumor area were sufficiently exposed to the laser irradiation. However, the normal bladder epithelium and muscle layer showed no histologic change. Similar reactions were found in papilloma of bladder which was considered as precancerous lesion. Thus, PDT may be beneficial to cancer prevention. Its role in prevention and treatment of bladder cancer should be further studied experimentally and clinically.