Christer Svensson

Residential radon exposure and lung cancer in Swedish women

A case-control study was undertaken to investigate the role of residential radon exposure for lung cancer. The study included 210 women with lung cancer diagnosed from 1983-1986 in the county of Stockholm and 191 hospital and 209 population controls. Interviews provided information on lifetime residences and smoking. Radon concentrations measured in 1,573 residences of the study subjects showed a lognormal distribution with arithmetic and geometric means of 127.7 and 96.0 Bq m-3, respectively. Lung cancer risks tended to increase with estimated radon exposure, reaching a relative risk of 1.7 (95% confidence interval: 1.0-2.9) in women having an average radon level exceeding 150 Bq m-3 (4 pCi L-1). Stronger associations were suggested in younger persons and risk estimates appeared to be within the same range as those projected for miners. However, further studies are needed to clarify the level of risk associated with exposure to residential radon.

Dietary factors and risk of lung cancer in never-smokers

We studied dietary risk factors for lung cancer among never‐smokers in a population‐based case–control study in Stockholm, 1989–1995. Study subjects were older than 30 years of age and had never smoked regularly. A total of 124 cases (35 men, 89 women) and 235 controls (72 men, 163 women) participated. Exposure information was obtained at interview with study subjects. The never‐smoking status was validated by interviews with next‐of‐kin. A protective effect was suggested for vegetables, mediated primarily by carrots (relative risk [RR], 0.7; 95% confidence interval [CI], 0.4–1.3, and 0.6, 0.3–1.1 for intermediate and high consumption of carrots, respectively). Non‐citrus fruits appeared to lower the risk as well, with RR 0.6, 95% CI 0.3–1.3 and 0.5, 0.3–1.0 for intermediate and high consumption, respectively. A protective effect with dose‐response was also seen for intake of beta‐carotene and total carotenoids. Increased risks were seen for cultured milk products in both genders (RR 2.0, 95% CI 1.1–3.9 for intermediate and 1.6, 0.9–2.9 for high consumption), but for milk only among male high consumers. Our results support evidence linking a diet rich in vegetables and non‐citrus fruit with decreased lung cancer risk and suggests that among vegetables, carrot consumption is the most important component or marker for this effect in Sweden. The results regarding milk products could be consistent with dietary fat as a risk factor for lung cancer, although a more comprehensive assessment of fat intake is necessary to explore this relation. Int. J. Cancer 78:430–436, 1998.

Smoking and Passive Smoking in Relation to Lung Cancer in Women

In a population based case-control study the association between female lung cancer and some possible etiological agents was investigated; 210 incident cases in Stockholm county, Sweden, and 209 age-matched population controls were interviewed about their exposure experiences according to a structured questionnaire. A strong association between smoking habits and lung cancer risk was found for all histological subgroups. Relative risks for those who had smoked daily during at least one year ranged between 3.1 for adenocarcinoma to 33.7 for small cell carcinoma in a comparison with never-smokers. All histological types showed strong dose-response relationships for average daily cigarette consumption, duration of smoking, and cumulative smoking. There was no consistent effect of parental smoking on the lung cancer risk in smokers. Only 38 cases had never been regular smokers and the risk estimates for exposure to environmental tobacco smoke were inconclusive. The high relative risks of small cell and squamous cell carcinoma associated with smoking may have implications for risk assessments regarding passive smoking.

Environmental tobacco smoke and lung cancer in nonsmokers : Does time since exposure play a role?

We conducted a population-based case-control study in Stockholm during 1989–1995 to investigate the risk of lung cancer from exposure to environmental tobacco smoke. The study base consisted of persons above 30 years of age resident in Stockholm County who had never smoked regularly (that is, one cigarette or more daily for 1 year). Cases of lung cancer were identified at the three major county hospitals responsible for diagnosis and treatment of lung cancer. A total of 124 cases (35 men and 89 women) and 235 population controls (72 men and 163 women) participated. The never-smoking status was validated by interviews with next-of-kin. The relative risk associated with ever-cohabiting with a smoking spouse was 1.2 [95% confidence interval (Cl) = 0.7–1.9]. Ever-exposure at work to environmental tobacco smoke carried a relative risk of 1.6 (95% CI = 0.9–2.9). Risks tended to be more elevated in high-exposure groups and with recent exposures. Both sources of environmental tobacco smoke seemed important, and considerable misclassification of total exposure occurred for each variable used separately, in particular for the less common spousal exposure. For those currently exposed to environmental tobacco smoke from the spouse, at work, or both, the relative risk was 2.6 (95% CI = 1.0–6.5). Our data imply that information from major sources of environmental tobacco smoke should be combined to avoid important misclassification and that timing of exposure should also be taken into consideration. (Epidemiology 1998;9:301–308)

Long-term Symptoms after External Beam Radiation Therapy for Prostate Cancer with Three or Four Fields

The aim of this study was to investigate whether external beam radiation treatment with three or four fields affects the risk of long-term distressful symptoms. The study included 145 patients who had been treated in Stockholm from 1993 to 1996 for localized prostate cancer. Bowel, urinary and sexual function as well as symptom-induced distress were assessed by means of a postal questionnaire 29-59 months after therapy. Among patients treated with a multileaf collimator, defecation urgency, diarrhoea and loose stools were more common after four fields than after three fields, but faecal leakage necessitating the use of pads and distress from the gastrointestinal tract were less common (although not statistically significantly so). Among bowel symptoms, the strongest association with gastrointestinal distress was found for faecal leakage. Three fields without a multileaf collimator entailed a higher risk of defecation urgency than three fields with a multileaf collimator. We conclude that the choice of three or four fields may imply a contrasting risk scenario for defecation urgency or diarrhoea in comparison with faecal leakage.

Indoor exposure to radon from the ground and bronchial cancer in women

SummaryA case-referent study on the possible association between radon emanating from the ground and bronchial cancer was carried out on 292 female lung cancer cases and 584 matched population referents. Both groups had lived for at least 30 years in the city of Stockholm, Sweden. The cases were diagnosed during 1972 to 1980 with oat-cell and other types of anaplastic pulmonary carcinomas. A sample of about 10% of the dwellings where cases and referents had lived was selected for measurements of radon and radon daughters. There was a relative risk of 2.2 (P = 0.01) for lung cancer associated with living in dwellings close to the ground in areas with an increased risk of radon emanation. Smoking habits did not appear to be a major confounding factor for this association, although a detailed evaluation was not possible. The measurements indicated increased radon daughter concentrations in ground level dwellings within radon risk areas where lung cancer cases had lived, suggesting that this exposure was of etiologic importance.

The Swedish National Care Programme for Anal Carcinoma: Implementation and Overall Results

The Swedish National Care Programme for Anal Carcinoma (SNCPAC) was instituted in order to create a uniform handling policy for anal cancer and thus to accrue a population-based material allowing unbiased analyses. This study evaluates the degree of implementation of the SNCPAC guidelines, and presents overall treatment results in a total of 356 patients with epidermoid cancer of the anus and the perianal region diagnosed in Sweden between 1985 and 1989. Primary treatment according to the guidelines was irradiation up to 40 Gy, Bleomycin was administered intramuscularly before the first 18 fractions. After a 3-week pause, radiotherapy was to be continued up to a dose of 60-64 Gy, if at least an almost complete response was achieved. Otherwise, the patient was recommended surgery within a week. The guidelines were applied in 90%, of cases where such treatment was possible. The 5-year tumour-specific survival rate was 72%. The survival rate was more favourable in perianal tumours (90%) than in anal canal tumours (68%, p < 0.01). The 5-year probability of having a preserved anus was 64% (anal canal/perianal 58%/91%, p < 0.001). Bleomycin did not appear to have any effect on treatment results. The care programme has had a rapid and almost complete nation-wide penetration, and h as created the desired uniformity allowing proper analyses. The treatment results also appear comparable with specialised referral centres.

A comparative study on different methods of measuring Rn concentrations in homes

Three methods of measuring 222Rn concentration in homes were compared. In 91 dwellings, measurements were made with thermoluminescence dosimeters (TLDs) for two weeks during the winter, with alpha track Track Etch type SF dosimeters (ATDs) for six months during the heating season and for one year. There was a high correlation between the TLD and the six-month ATD values (r = .83) and between the six-month and the one-year ATD values (r = .80). On the average, however, the arithmetic and geometric means of the ATD (six-month) values were approximately 50 Bq m-3 higher than the TLD values (p less than .0001). The six-month ATD values also were, on the average, approximately eight percent higher than the one-year values. This difference is probably caused by decreased ventilation during the colder part of the year. The results indicate that the measurement methods under study may be of value for exposure assessments in epidemiologic studies, but also that estimates of risk per unit radiation exposure should be interpreted with caution.