Paradoxical effect of radiation on tumor incidence in the rat: implications for radiation therapy.

The high incidence of leukemia in the Fischer rat is reduced by radiation to an incidence below that seen spontaneously. Fractionating the radiation decreased this effect. In contrast, mammary tumors increased with dose until reaching a plateau at the highest doses. Fractionation had little effect. These results are consistent with a hypothesis suggesting that tumor incidence due to radiation is the result of competing processes of tumor induction and cell killing.

The effect of thyroid hormone administration upon survival in patients with differentiated thyroid carcinoma.

Seven hundred sixty-one patients with operable differentiated thyroid carcinoma were treated between 1931 and 1970. Median follow-up time was 18 years and ranged from 5 to 40 years. Sixty-three percent of the patients were followed more than 15 years, and 46% were followed more than 20 years. Because resections usually spared sufficient thyroid tissue for homeostasis, thyroid hormone was not routinely prescribed after operations performed before 1960. Altogether 244 patients with papillary carcinoma and 76 patients with follicular carcinoma received thyroid hormone, while 296 patients with papillary carcinoma and 45 patients with follicular carcinoma did not receive thyroid hormone after operation. With papillary carcinoma, 14% of men greater than 40 and women greater than 50 years of age (high risk) but only 2% of men less than or equal to 40 years of age and women less than or equal to 50 years of age (low risk) died of disease (P 0.0001). Twenty-six percent of high-risk but only 4% of patients with low-risk follicular cancer died (P 0.0001). However, there was no statistically significant improvement in survival times with use of thyroid hormone when patients were categorized by risk group and pathology. These data support the importance of age and sex in previously described risk groups; these factors supersede the effects of adjuvant treatment. This absence of effect on survival times calls into question current recommendations for routine use of thyroid hormone after surgical therapy. Conceptually, such absence of adjunctive hormone effect on survival time after operation is similar to hormonal effects in other endocrine cancers, which may nevertheless provide good palliation in some cases.

Input-voltage method of bone-conduction calibration.

Several methods have been proposed for calibrating the bone-conduction section of an audiometer. Because of its low cost and ease of implementation, the input-voltage method is attractive. Only one previous investigation has assessed this calibration method and found it to be lacking. With the availability of updated "required voltages," a reexamination of this calibration method was warranted. Audiometric corrections were determined for 21 combinations of audiometers and bone vibrators at five test frequencies with an artificial-mastoid system. These corrections were compared with those determined with the input-voltage method. The latter yielded corrections that agreed directly with or deviated no more than 5 dB from artificial-mastoid corrections 93.4% of the time and deviated by 10 dB only 6.6% of the time. The use of the input-voltage method for clinical calibration is advocated in the absence of an artificial mastoid.

The manual LOT test.

This study was conducted to determine the feasibility of a manual variation of the lengthened off-time (LOT)-Békésy test. The procedure requires that the audiologist vary the attenuator of an audiometer while the signal paradigms of the LOT test are delivered to the patient. Ten nonorganic hearing loss subjects were tested using the automatic LOT test and the manual LOT test. Results were equivalent to the automatic test lending support for the new procedure. The technique can be used with most wide-range audiometers without the additional expense of an automatic recording device.

Histologic changes seen in the hepatic parenchyma and in metastatic nodules following hepatic dearterialization.

Hepatic dearterialization was performed on four patients in an attempt to provide symptomatic relief from metastic carcinoma in the liver. Interruption of hepatic arterial blood supply causes necrosis in larger metastatic tumor deposits, but very small nodules are unaffected by the procedure; this observation supports experimental studies on tumor angiogenesis factor. Interruption of hepatic arterial blood supply results in nonspecific ischemic changes to the hepatic parenchyma, which responds with small nests of regenerating liver cells. This finding appears to support the work of Plengvanit on revascularization of the liver after hepatic artery ligation.

Dearterialization of the liver for metastatic cancer. Clinical, angiographic and pathologic observations.

Five cases of dearterialization of the liver for metastatic cancer are presented. Subjective and objective improvement was accomplished in three patients. Pre- and postoperative arteriography demonstrates the extent of devascularization and the routes of reestablished collateral. Microscopic studies demonstrated effects on tumor and on hepatic parenchyma and biochemical data indicate the extent and duration of hepatic dysfunction.

Factors in the prognosis of gastric lymphoma.

The tumor-nodes-metastases (TNM) staging classification for gastric carcinoma was applied to 50 consecutive cases of primary gastric lymphoma. Survival statistics were obtained for each respective stage category and were remarkably similar to survival statistics for gastric carcinoma. Overall, patients with primary gastric lymphoma have a much better prognosis for survival than patients with gastric carcinoma since the latter present with far more frequent serosal penetration and nodal and distant metastases. Penetration of gastric lymphoma beyond the serosa is associated with a significantly decreased 5-year survival rate from 88 to 24%, and the presence of perigastric nodal involvement decreased the survival rate from 88 to 32%.

Risk factor analysis in differentiated thyroid cancer.

Six hundred patients with primary differentiated thyroid carcinoma had follow-up studies for a minimum of 15 years and a maximum of 45 years. Recurrence rate and death rate were significantly different in defined high-risk and low-risk groups of patients. These basic risk groups were defined by age and sex alone; low risk consisted of men 40 years of age and younger and women 50 years of age and younger whereas the high-risk group were older patients. Recurrence and death rates in patients at high risk were 33% and 27% while respective figures for patients at low risk were 11% and 4%. In more recent years these results have shown significant improvement. Basic risk group definition outweighed the effect of pathologic type, local disease extension, type of treatment, and site of recurrence or metastasis. For instance, radioactive iodine cured 70% of patients at low risk with metastatic disease but only 10% of patients at high risk. Less aggressive biologic behavior of thyroid cancer before the age of menopause implies that an estrogen-rich milieu may alter the effects of initiating and promoting factors in carcinogenesis. It also suggests that therapeutic trials of estrogen be undertaken in progressive metastatic differentiated thyroid cancer.

Changing clinical, pathologic, therapeutic, and survival patterns in differentiated thyroid carcinoma.

Records of 792 patients with differentiated thyroid carcinoma seen at the Lahey Clinic Foundation over a 40-year period were analyzed; 631 patients had a minimum followup period of 15 years. Differentiated types currently constitute nearly 90% of thyroid carcinomas. The clinical presentation has improved substantially through the years, and the results of treatment generally have improved. The per cent of patients with primarily incurable and locally unresectable disease or distant metastases has decreased from 7% before 1950 to 1% currently, and this group resulted in almost one third of the total fatalities and one half of fatalities within the first 5 years after treatment. Clear relationships were demonstrated between older age, men, extraglandular extension, blood vessel invasion, major capsular involvement, multifocal disease, and higher mortality rates. Lymph node metastases were found to exert a protective effect in all categories of disease analyzed, and this effect was directly related to the number of lymph node metastases present such that no deaths occurred in those patients who had more than 10 node metastases. Surgical treatment recommended is subtotal thyroidectomy for patients at high risk of death from disease as defined by combinations of age, sex, and extraglandular extension. Patients at low risk or with small carcinomas can be treated satisfactorily by lobectomy. Lymph node resections should be of a limited type or a modified neck dissection and should be performed only therapeutically. No improvement, as judged by mortality or recurrence rates, could be demonstrated by the use of radio therapy after surgery, and its use should be discouraged. Thyroid hormone administered for suppression of endogenous thyroid-stimulating hormone production improved mortality rates significantly in patients with papillary and mixed forms of carcinoma in all age groups but did not affect survival in patients with follicular carcinoma of the thyroid.20