Reproductive factors in the aetiology of breast cancer

An interview study of 1,362 breast cancer cases and 1,250 controls identified through a multi-centre screening project allowed an evaluation of reproductive determinants of breast cancer. Risk increased linearly with age at first livebirth; women with a birth after age 30 showed 4-5-fold excess risks compared to those with a birth prior to 18, while the risk for nulliparous women resembled that for women whose first birth was in their late twenties. The protection conferred by an early first pregnancy prevailed for pregnancies that ended in a livebirth or stillbirth, but not for those that terminated in other outcomes. Among parous women, a first trimester abortion prior to a livebirth was not associated with an elevated risk, except in the event of multiple miscarriages (RR = 2.2, 95% Cl 0.9-5.1). Although numbers were limited, women who reported an induced abortion in the absence of ever having a livebirth showed some elevation in risk. Age at first livebirth explained most associations, but some residual reduction in risk was noted for multiparous women and those with several births at an early age. There was evidence that delays in birth after marriage increased risk, but this did not explain the high risk associated with late age at first birth.

Coffee drinking and risk of bladder cancer

The relationship between coffee drinking and risk of bladder cancer was assessed with the use of data from a case-control study of bladder cancer. Incident cases (2,982) and general population controls (5,782) were interviewed. Overall, the relative risk (RR) of bladder cancer for subjects who had ever drunk coffee was estimated as 1.4 (95% confidence interval = 1.1-1.8). There was no consistent relation between the RR estimate and the current consumption level. Among men who drank coffee, those who drank more than 49 cupfuls of coffee per week had an apparent excess in risk, but women who drank that much had an apparent deficit in risk.

Epidemiology of minimal breast cancer

A case-control study conducted within the Breast Cancer Detection Demonstration Project allowed comparison of epidemiologic factors for benign breast diseases (n = 1,404), in situ cancer (n = 199), small (less than or equal to 1 cm) invasive cancer (n = 210), and larger invasive cancer (n = 788). Control subjects consisted of program participants who were not recommended for breast biopsy. Relationships were similar for small and larger invasive tumors, both showing associations with family history of breast cancer, age at first live birth, history of bilateral oophorectomoy, and obesity. In situ cancer was affected by family history and age at first childbirth but not by oophorectomy or obesity. These findings support the notion that "minimal" breast cancer is indeed cancer. In addition, the results suggest that hormonal influences early in life may initiate the carcinogenic process, while those that operate later may enhance the progression from in situ to invasive disease.

Oral contraceptives and breast cancer

A case-control interview study, conducted among participants in the Breast Cancer Detection Demonstration Project and involving 963 breast cancer cases and 858 controls, allowed evaluation of the risk of breast cancer associated with use of oral contraceptives. Overall, there was no association between use and risk of disease (RR = 1.1). In addition, there was no indication of increasing risk with years of use or years since initial use, despite slight excess risks observed among users of high-dose preparations. Premenopausal women who used the pill after the age of 40 demonstrated approximately a 50% increased risk, possibly as a result of artificial prolongation of a premenopausal rate of disease incidence. Non-significant excess risks associated with pill use were also seen among premenopausal women who reported a family history of breast cancer in a sister (RR = 3.6) or previous biopsies for benign breast disease (RR = 3.2). The latter excess was limited to women whose use of the pill preceded a first biopsy, suggesting that the types of lesions requiring biopsy among current long-term pill users may be those that predispose to breast cancer.

Use of hair dyes and risk of bladder cancer

The relation between use of hair dyes and risk of bladder cancer was assessed using data from a case-control study of bladder cancer. Incident cases (2982) and general population controls (5782) were interviewed. The overall estimate of relative risk of bladder cancer for users of hair dyes was 1.0 (95%) confidence interval, 0.9 to 1.2) compared to nonusers. No consistent pattern of association was detected between bladder cancer risk and various indices of timing or intensity of exposure to hair dyes. Various explanations of the lack of association are discussed.

Interaction of familial and hormonal risk factors for breast cancer

A case-control study, conducted among participants in the Breast Cancer Detection Demonstration Project, obtained detailed information on family history of breast cancer and other risk factors from 1,362 breast cancer patients and 1,250 control subjects. An affected first-degree relative was reported by 22.4% of the patients and 12.2% of the control subjects. This finding was associated with a twofold increased risk of breast cancer, although greater elevations in risk were seen in younger study subjects and in those reporting both an affected mother and a sister. Analysis of other risk factors showed that, compared to women without a family history of breast cancer, control subjects with a family history of breast cancer tended to have early or late menarche, were older at first childbirth, and were younger at oophorectomy. In addition, the effect of family history on breast cancer risk was modified by age at menarche, but not by age at first birth or type of menopause. These findings suggest that familial susceptibility to breast cancer may be mediated through hormonal factors that operate early in a woman's life. A synergistic relationship was also observed between family history of breast cancer and the occurrence of multiple biopsies for benign breast disease, although the mechanisms for this relationship remain to be elucidated.

Esophageal cancer among black men in Washington, D.C. II. Role of nutrition

A case-control study of esophageal cancer was conducted among the black male residents of Washington, D.C., to find reasons for the exceptionally high risk in this population. The next of kin of 120 esophageal cancer cases who died during 1975-77 and of 250 D.C. black males who died of other causes were interviewed. Five indicators of general nutritional status--fresh or frozen meat and fish consumption, dairy product and egg consumption, fruit and vegetable consumption, relative weight (wt/ht2), and number of meals eaten per day--were each significantly and inversely correlated with the relative risk of esophageal cancer. Associations with other food groups were not apparent. The least nourished third of the study population, defined by any of these five measures, was at twice the risk of the most nourished third. None of these associations was markedly reduced by controlling for ethanol consumption, the other major risk factor in this population; smoking; socioeconomic status; or the other nutrition measures. When the three food group consumption measures were combined into a single overall index of general nutritional status, the relative risk of esophageal cancer between extremes was 14. Estimates of the intake of vitamin A, carotene, vitamin C, thiamin, and riboflavin were inversely associated with relative risk; but each micronutrient index was less strongly associated with risk than were the broad food groups that provide most of the micronutrient. Thus no specific micronutrient deficiency was identified. Instead, generally poor nutrition was the major dietary predictor of risk and may partially explain the susceptibility of urban black men to esophageal cancer.

Conjugated estrogens and breast cancer risk in women

The relationship between conjugated estrogen(s) (CE) and breast cancer was investigated by the examination of the records of 345 women with newly diagnosed breast cancer and 611 healthy controls belonging to a prepaid health plan. Use of CE was associated with a 40% elevation in risk [relative risk (RR) = 1.4; 95% confidence interval-1.0-2.0]. The RR was 1.3 for menopausal women with intact ovaries and 1.5 for those with ovaries removed. There was statistically significant evidence of a dose-response relationship with the three measures of dose evaluated. RR's rose to about twofold for women with 10 or more CE prescriptions noted in their charts, for those with 5 years or more between their first and last prescription, and for those with a usual daily dose of 1.25 mg or more. The RR associated with having ever used CE and with long-term use was highest among those women with a family history of breast cancer. These data support the hypothesis that long-term use of CE is associated with increased breast cancer risk.

Protocol for a study of nutritional factors and the low risk of colon cancer in Southern retirement areas

Colon cancer shows a distinct geographic pattern in the United States, with mortality rates in the Northeast exceeding those in the South by about 50%. The North-South gradient remains even after adjustment for differences in urbanization and socioeconomic status. Those counties in the South that attract large numbers of retirees from the North retain the low colon mortality rates characteristic of the South, even at older ages. This observation implies either that certain life-style changes associated with migration at retirement rapidly reduce the risk of colon cancer or that individuals migrate selectively, based on some correlate of health. A specific hypothesis related to the former possibility is that consumption of fruits and vegetables, and the associated vitamin C, carotene, and fiber, is elevated in the South and related to the reduced risk of colon cancer. A protocol is presented for a case-control interview study in Southern retirement areas to assess these possible explanations. A detailed residential history, as well as information on frequency of consumption of specific foods, food groups, and micronutrients, will be collected by interview and will be complemented by selected serum micronutrient determinations and fecal mutagenicity assays.

Bladder cancer in pet dogs: a sentinel for environmental cancer?

Proportional morbidity ratios (PMRs) were calculated for cancers, by site or type, in 8760 pet dogs seen at 13 veterinary medical teaching hospitals in the United States and Canada. A significant positive correlation was seen between the PMRs for canine bladder cancer and the overall level of industrial activity in the host county of the hospital. An analysis of mortality from bladder cancer among white men and women in the same US counties showed similar correlations with industrial activity. Canine bladder cancer could be a sentinel condition whose investigation in locales might lead to early identification of carcinogenic hazards in the general environment.

Gynecologic cancer treatment: risk factors for therapeutically induced neoplasia

Therapeutic intervention in a course of illness, while producing the desired result, also may have some adverse long-term effects on the patient. Second malignancies are one of the known complications of therapy. The treatments of gynecologic cancers by surgery, irradiation and chemotherapy have been associated with subsequent neoplasms. Care must be exercised in associating previous therapy and a subsequent malignancy. "Naturally" occurring second cancers must be separated from those which are iatrogenic. Associations in the literature have been made involving malignancies as a sequelae of prior gynecologic therapy. The use of normal skin from the thigh to fabricate an artificial vagina has resulted in more squamous cell carcinomas than expected. Alkylating agents used in the treatment of ovarian cancer and other diseases have been shown to lead to an increased risk of leukemia. Irradiation therapy, however, has not yet been shown to be related to leukemia in cervical cancer patients. The incidence of lymphoma and uterine, urinary bladder and colon carcinomas has been associated with prior irradiation for gynecologic disease. The literature regarding the therapeutically induced risk factors in gynecologic therapy is reviewed and areas of our knowledge that require more investigation are identified.

Drug-induced cancer

This report reviews the medicinal agents that have been linked to human cancer, with emphasis on recent evidence implicating estrogenic compounds such as DES, menopausal estrogens, and oral contraceptives. Attention is also given to drugs that have fallen under suspicion and requires further epidemiologic evaluation. The detection of drug-cancer associations not only influences clinical and public health practice, but may also provide insights into mechanisms of carcinogenesis. The clinician contributes to the prevention of drug-induced cancer by being alert to iatrogenic hazards and cooperating in epidemiologic investigations, by weighing risks versus benefits in individual cases, and by discussing with patients the rationale and risks of proposed forms of therapy.

Cryptococcal pyelonephritis and disseminated cryptococcosis in a renal transplant recipient

Symptomatic cryptococcal pyelonephritis, meningitis, and disseminated cryptococcosis are described in a renal cadaver transplant recipient who subsequently died of Klebsiella pneumoniae sepsis. The presence of cryptococcuria and a subsequent positive CSF India ink stain led to the initial diagnosis of disseminated cryptococcosis. Therapy with 0.511 g of amphotericin B and 112.5 g of flucytosine for four weeks did not eradicate Cryptococcus from the kidney and was associated with hepatotoxicity. The importance of urinary examination and culture for C neoformans is emphasized. Cryptococcal pyelonephritis should be considered in the differential diagnosis of allograft rejection in the renal transplant patient.

Cancer mortality among workers exposed to zinc chromate paints

To evaluate the carcinogenicity of chromium compounds among user industries, the proportionate mortality experience of spray painters exposed to zinc chromate primer paints and electroplaters exposed to chromic acid in the aircraft maintenance industry was examined. Compared to the mortality patterns of U.S. white males, no excess of cancer was found in the 48 deaths among electroplaters. Analysis of the 202 deaths among spray painters revealed a significant excess of cancer, primarily of the respiratory tract. The relative increase of respiratory cancer showed a positive gradient with the length of estimated exposure time, and was confined to painters whose interval from first employment to death was at least 20 years. The findings consistent with occupational exposure to chromium compounds, previously shown to be carcinogenic in manufacturing processes, but the effect of other paint constituents, tobacco smoking, or methodologic limitations could not be discounted.