We performed a retrospective study of 859 patients with papillary thyroid cancer, who had received their primary treatment at the Mayo Clinic during the period 1946 through 1970. The maximal follow-up was 39 years. All but 2 patients underwent a thyroid operation; 319 (37%) had metastatic cervical nodes. Of the 800 patients without distant metastatic lesions on initial examination who underwent a potentially curative surgical procedure, postoperatively 7% had nodal metastatic lesions, 6% had a local tumor recurrence, and 5% had a distant metastatic lesion. In patients who had intrathyroidal tumors initially, postoperative local recurrences or distant metastatic lesions resulted in a 10-year cancer mortality of 17 and 41%, respectively; in those with extrathyroidal tumors, postoperative recurrences were associated with significantly higher death rates. Death from thyroid cancer was highly associated with the following factors: age more than 50 years, male sex, tumor size, tumor grade, initial extent of disease, and absence of Hashimoto's disease. Earlier studies of Mayo patients treated between 1926 and 1960 described no deaths due to thyroid cancer in patients with occult tumors (1.5 cm or less). Four such patients were identified among our 859 patients; all had been examined and treated after 1961. To date, 56 (6.5%) of the 859 patients have died as a result of papillary thyroid cancer. In this study, in which 16% of patients underwent total thyroidectomy and 3% had radioiodine ablation, the overall mortality observed at 30 years was only 3% above that expected.
The National Cancer Institute of the United States recently sponsored three large-scale, randomized controlled trials of screening for early lung cancer. The trials were conducted at the Johns Hopkins Medical Institutions, the Memorial Sloan-Kettering Cancer Center, and the Mayo Clinic. Participants were middle-aged and older men who were chronic heavy cigarette smokers and thus at high risk of developing lung cancer. Screening procedures were chest radiography and sputum cytology, the only screening tests of established value for detecting early stage, asymptomatic lung cancer. In the Hopkins and Memorial trials the study population was offered yearly chest radiography plus sputum cytology every 4 months. The control population was offered yearly chest radiography only. In these trials the addition of sputum cytology appeared to confer no lung cancer mortality rate advantage. The Mayo Clinic trial compared offering chest radiography and sputum cytology every 4 months to offering advice that the two tests be obtained once a year. This trial demonstrated significantly increased lung cancer detection, resectability, and survivorship in the group offered screening every 4 months compared with the control group. However, there was no significant difference in lung cancer mortality rate between the two groups. The statistical power of these trials was somewhat limited. Nevertheless, results do not justify recommending large-scale radiologic or cytologic screening for early lung cancer at this time.
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