A retrospective study of cancer at high risk sites in the region of the head and neck was undertaken at the Bombay Cancer Registry, in 1968, to evaluate the effects of tobacco when chewed or smoked. There is sufficient evidence available today to indict chewing and smoking of tobacco as factors of great importance in the etiology of oral, pharyngeal, laryngeal, and esophageal cancers—the most common sites affected by the disease in Greater Bombay. This cause/ effect association is probably as intimate as that of cigarette smoking and lung cancer. The carcinogenic action of chewed tobacco is particularly evident at those sites where the bolus is retained in place for any length of time. Likewise, inhalation of tobacco fumes during the act of smoking produces a stream of gas and of solid particles which impinges directly on the oropharynx and especially on the soft palate initially and exposes smokers to the increased risk of developing cancer at exactly these posterior sites in the oropharynx, rather than more anteriorly in the oral cavity where the tissues do not directly bear the brunt of the onslaught from the smoke. It is revealing to find that the high risk sites involved in tobacco chewers appear to be the least affected in smokers, and vice versa.

Summary.-Evidence is presented which indicates that S-(1,2,3,4-tetrahydro-2-hydroxy-l-naphthyl)-L-cysteine (THN-cysteine), formed by the reaction of 1,2-epoxy-THN with cysteine, can be incorporated into protein. The position of incorporation of THN-cysteine into protein would depend on whether the epoxide of THN reacts with cysteinyl-tRNACYs or with cysteine. In both cases, the mechanism of incorporation of THN-cysteine into protein is the same as for the natural amino acids. For example, the incorporation of THN-cysteinyl-tRNACYs is stimulated by Poly-UG, the code for tRNACys, and would be expected to be substituted for cysteine in protein being synthesized, whereas THN-cysteine not previously esterified to tRNA is activated by the isoleucyl-and valyl-RNA synthetases, and its incorporation is stimulated by Poly-AU and Poly-UG, respectively. Consequently, in this case, THN-cysteine would substitute for isoleucine and valine during protein synthesis.

Twelve patients with lingual thyroid are reviewed. Two of these patients had a follicular carcinoma in the ectopic gland and both are well 5 and 16 years after treatment. The diagnosis is essentially clinical but confirmation may be made with a thyroid scan. Six patients were treated conservatively with thyroxine with good results. Six patients were treated by surgical excision, 2 undergoing autotransplantation of the excised gland into the anterior abdominal wall.

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Sera of patients with breast cancer, of healthy women from the United States, East India, East Africa, and China, and of healthy women of American and Parsi families in which breast cancer occurred in several family members were assayed for levels of antibody reactive with the murine mammary tumor virus (MuMTV) by an enzyme-linked immunosorbent assay. Increased levels of antibody to MuMTV (absorbance -0.4) were found in sera of 18.6% ofAmerican patients with breast cancer and of 2.8% of healthy American women and in 38% of patients from India and 61.9% from East Africa (healthy, 26.9%). In contrast, antibody reactive with MuMTV was found in <5 of women with breast cancer from mainland China (healthy Chinese, 5.0%). Differences in serum MuMTV antibody levels between breast cancer patients in the four groups were found to be significant (P < 0.0001). Studies of two families from the United States and of one Parsi family from India with genetic propensity to breast cancer showed that high levels ofantibody to MuMTV were found in 33%, 71%, and 23% of healthy family members, respectively. The antibody to MuMTV was readily absorbed with purified MuMTV and gp52. In contrast, fetal calf serum, murine type C retroviruses, or erythrocytes from various species failed to absorb the antibody. A relationship between human breast cancer and murine mammary tumor virus (MuMTV) has been suggested from several observations. RNA partially homologous to the MuMTV genome was identified in human breast cancer tissue (1). Lymphocytes from individuals with breast cancer were shown to proliferate after stimulation by MuMTV (2, 3). Sera from breast cancer patients decreased the infectivitity of MuMTV in mice (4), suggesting the presence of antibodies against the virus. More recently, using immunoperoxidase staining, Mesa-Tejada et al. (5) found that antigen reacting with antibody to the envelope glycoprotein of MuMTV (gp52) could be detected in breast cancer tissue. Ohno et al. (6) have now demonstrated that this crossreactivity is directed to the protein moiety ofgp52 and not the carbohydrate.In prior studies using a virolytic assay with complement and antibody, we found that antibodies reactive with MuMTV are present in sera of approximately 20% of American women with breast cancer (7). Sera of age-matched healthy women and of patients with other cancers had such antibodies in lower frequency. We developed a method to detect these antibodies directly by using MuMTV and an enzyme-linked immunosorbent assay (ELISA) (8). With this method also we found that sera of approximately 25% of American women with breast cancer had antibodies to MuMTV. Approximately 10% ofwomen with benign cystic disease of the breast also had such antibodies in their sera (8). Reactivity was inhibited by the membrane proteins of MuMTV (gp52 and gp34) but not by the core antigen (p28) (9).We now report results on the specificity of the human antibody for MuMTV, the geographic distribution of the antibody in breast cancer patients, and analyses of families in...