[Is thyroid cancer a severe cancer? (Prognostic study of 800 surgically-treated cases of which 143 nodular differentiated cancers were followed-up for more than 20 years)].
The prognosis of thyroid carcinoma has always been difficult to appreciate because this rather rare carcinoma is polymorph and subject to some very late recurrencies. For these reasons an acceptable prognostic evaluation is only possible with an important material and very long follow-up. From 800 patients operated by the author, 102 (13%) had an extra-capsular tumor, which means for all authors a very poor prognosis. Still two groups must be separated: the anaplastic extracapsular tumors (33/102) gave a very low life expectancy with 17% survival at 5 years and no patient surviving at 8 years. In contrast the differentiated extracapsular tumors, mainly papillary, gave an unexpected survival rate of 35% at 15 years. The more frequent nodular form of differentiated carcinoma (698/800 = 87%) has a much better prognosis, but his slow evolution needs a long follow-up observation. From 160 patients operated on before 1971, 143 (90%) could be all followed during 20 years or more. The over-all survival rate at the 20th year is 83% with 76% of patients free of any recurrence. The analysis of several factors showed that the extension of the primitive operation (lobectomy or total thyroidectomy) does not influence the long term results. More reliable prognostic factors are the degree of histologic differentiation of the tumor, and the age of the patient. Finally, in spite of an excellent overall long-term prognosis, three very late recurrencies were observed in the group of 143 patients followed more than 20 years, respectively 21, 22 and 31 years after the first operation. This makes impossible the certitude of definitive cure of any thyroid cancer.