Electrospun nanofibers for neural tissue engineering

Biodegradable nanofibers produced by electrospinning represent a new class of promising scaffolds to support nerve regeneration. We begin with a brief discussion on the electrospinning of nanofibers and methods for controlling the structure, porosity, and alignment of the electrospun nanofibers. The methods include control of the nanoscale morphology and microscale alignment of the nanofibers, as well as the fabrication of macroscale, three-dimensional tubular structures. We then highlight recent studies that utilize electrospun nanofibers to manipulate biological processes relevant to nervous tissue regeneration, including stem cell differentiation, guidance of neurite extension, and peripheral nerve injury treatments. The main objective of this feature article is to provide valuable insights into methods for investigating the mechanisms of neurite growth on novel nanofibrous scaffolds and optimization of the nanofiber scaffolds and conduits for repairing peripheral nerve injuries.

Gold nanocages covered by smart polymers for controlled release with near-infrared light

Photosensitive caged compounds have enhanced our ability to address the complexity of biological systems by generating effectors with remarkable spatial/temporal resolutions. The caging effect is typically removed by photolysis with ultraviolet light to liberate the bioactive species. Although this technique has been successfully applied to many biological problems, it suffers from a number of intrinsic drawbacks. For example, it requires dedicated efforts to design and synthesize a precursor compound for each effector. The ultraviolet light may cause damage to biological samples and is suitable only for in vitro studies because of its quick attenuation in tissue. Here we address these issues by developing a platform based on the photothermal effect of gold nanocages. Gold nanocages represent a class of nanostructures with hollow interiors and porous walls. They can have strong absorption (for the photothermal effect) in the near-infrared while maintaining a compact size. When the surface of a gold nanocage is covered with a smart polymer, the pre-loaded effector can be released in a controllable fashion using a near-infrared laser. This system works well with various effectors without involving sophisticated syntheses, and is well suited for in vivo studies owing to the high transparency of soft tissue in the near-infrared region.

Probing the photothermal effect of gold-based nanocages with surface-enhanced Raman scattering (SERS)

The conformation of molecules on a metallic nanoparticle’s surface is sensitive to temperature variations and can be easily monitored in situ by SERS. Excitation of the metallic nanoparticle for SERS can concurrently induce a photothermal effect whereby the light absorbed by the nanoparticle is released as heat. From the SERS spectra, we could derive the changes in temperature at the surface of a nanoparticle during the photothermal effect.

Secondary cancers after a lung carcinoid primary: A population-based analysis

Carcinoid tumors of the lung were first described in 1937, yet little is known about their etiology. The aim of the present investigation was to determine if there was excess risk of secondary cancers in a population-based sample after a lung carcinoid tumor diagnosis which may provide insight to the etiology. Subjects were 1882 cases diagnosed with carcinoid tumors of the lung between 1988 and 2000 whose information was obtained from the Surveillance, Epidemiology and End Results (SEER) Program database. Standardized incidence ratios were calculated by dividing the observed number of second primary cancers by the expected number of cancers. Excess risk of breast cancer was seen following diagnosis of a carcinoid tumor (SIR=1.80 95% CI 1.22-2.55). When stratified by time after diagnosis, excess risk of breast cancers in women was seen in the first 5 years after carcinoid diagnosis (SIR=1.68 95% CI 1.08-2.50) but fewer than expected breast cancers were diagnosed greater than 5 years after carcinoid diagnosis (SIR=0.29 95% CI 0.09-0.68). Prostate cancers also occurred 2.8 times more often than expected (95% CI 1.66-4.43), with risk being elevated only in the first 5 years post-carcinoid diagnosis. Development of lung carcinoids may be the result of genetic predisposition or environmental exposures, particularly those that are hormonally related. The role of genetics and sex hormones in lung carcinoid development, as well as the identification of other risk factors, should be explored.

CYP1A1 and CYP1B1 polymorphisms and risk of lung cancer among never smokers: a population-based study

The cytochrome P450 (CYP) superfamily of enzymes catalyse one of the first steps in the metabolism of carcinogens such as polycyclic aromatic hydrocarbons, nitroaromatics and arylamines. Polymorphisms within the CYP1A1 gene have been shown to be associated with lung cancer risk, predominantly among Asian populations. Despite functional evidence of a possible role of CYP1B1 in lung cancer susceptibility, only a few studies have evaluated polymorphisms in this gene in relation to lung cancer susceptibility. This population-based study evaluates polymorphisms in both of these CYP genes within never smokers, most of whom had environmental tobacco smoke (ETS) exposure. Cases (n = 160) were identified through the metropolitan Detroit Surveillance, Epidemiology and End Results program, and age, sex and race-matched population-based controls (n = 181) were identified using random digit dialing. Neither CYP1A1 MspI nor CYP1A1 Ile(462)Val was associated with lung cancer susceptibility among Caucasians or African-Americans. Among Caucasians, however, CYP1B1 Leu(432)Val was significantly associated with lung cancer susceptibility odds ratio (OR) for at least one valine allele = 2.87 [95% confidence interval (CI) 1.63-5.07]. Combinations of this Phase I enzyme polymorphism along with selected Phase II enzyme polymorphisms (GSTM1 null, GSTP1 Ile(105)Val and NQO1 C(609)T) were evaluated. The combination of CYP1B1 Leu(432)Val and NQO1 C(609)T appeared to be associated with the highest risk of lung cancer (OR = 4.14, 95% CI 1.60-10.74), although no combinations differed significantly from the risk associated with CYP1B1 Leu(432)Val alone. When individuals were stratified by household ETS exposure (yes/no), CYP1B1 Leu(432)Val alone and in combination with Phase II enzyme polymorphisms was more strongly associated with increased lung cancer susceptibility among those with at least some household ETS exposure. Additional studies will be required to further validate these findings among never smokers and to evaluate the effects of this polymorphism among smoking populations as well.

Combinations of glutathione S-transferase genotypes and risk of early-onset lung cancer in Caucasians and African Americans: a population-based study

Polymorphisms in GSTM1, GSTT1 and GSTP1 genes in humans are associated with the reduction of enzymatic activity toward several substrates, including those in tobacco smoke. To investigate the potential role these polymorphisms have, as modulators of early-onset lung cancer risk, a population-based case-control study involving early-onset lung cancer cases was performed. Biological samples were available for 350 individuals diagnosed <50 years of age identified from the metropolitan Detroit Surveillance, Epidemiology and End Results (SEER) program and 410 cases of age, race and sex-matched controls ascertained through random digit dialing. African Americans carrying at least one G allele at the GSTP1 locus were 2.9-fold more likely to have lung cancer compared with African Americans without a G allele after adjustment for age, sex, pack years of smoking and history of lung cancer in a first-degree relative (95% CI 1.29-6.20). African Americans with either one or two risk genotypes at the GSTM1 and GSTP1 loci were at increased risk of having lung cancer compared with those having fully functional GSTM1 and GSTP1 genes (OR = 2.8, 95% CI 1.1-7.2 and OR = 4.0, 95% CI 1.3-12.2, respectively). No significant single gene associations between GSTM1, GSTT1 or GSTP1 and early-onset lung cancer were identified in Caucasians, after adjusting for age, sex, pack years and family history of lung cancer. However, our results suggest that specific combinations of glutathione S-transferase polymorphisms increase the risk of early-onset of lung cancer. Joint analysis of these genotypes may identify individuals who are at a higher risk of developing early-onset lung cancer with a greater certainty than single gene studies.

GSTM1, GSTT1 and GSTP1 polymorphisms, environmental tobacco smoke exposure and risk of lung cancer among never smokers: a population-based study

Glutathione S-transferases detoxify polycyclic aromatic hydrocarbons found in tobacco smoke by glutathione conjugation. Polymorphisms within the GSTM1, GSTT1 and GSTP1 genes, coding for enzymes with deficient or reduced activity, have been studied as potential modifiers of lung cancer risk. It is hypothesized that risk associated with potential susceptibility gene polymorphisms might be most evident at low levels of exposure. Never smokers developing lung cancer represent a highly susceptible subset of the population, exposed to tobacco carcinogens only through environmental tobacco smoke. This population-based case-control study examines the association between GSTM1, GSTT1 and GSTP1 genotypes and lung cancer in one of the largest samples of never smokers to date. Cases (n = 166) were identified through the metropolitan Detroit Surveillance, Epidemiology and End Results (SEER) program and age- and race-matched population-based controls (n = 181) were identified using random digit dialing. Overall, there was no significant association between single or combinations of genotypes at GSTM1, GSTT1 or GSTP1 and lung cancer risk after adjustment for age, race, sex and household ETS exposure in years. However, in never smokers exposed to 20 or more years of household ETS, carrying the GSTM1 null genotype was associated with a 2.3-fold increase in risk [95% confidence interval (CI) 1.05-5.13]. Individuals in this high ETS exposure category carrying the GSTM1 null and the GSTP1 Val allele were at over 4-fold increased risk of developing lung cancer (OR = 4.56, 95% CI: 1.21-17.21). These findings suggest that in the presence of ETS, the GSTM1 genotype both alone and in combination with the GSTP1 genotype alters the risk of developing lung cancer among never smokers.

NQO1 T allele associated with decreased risk of later age at diagnosis lung cancer among never smokers: results from a population-based study

The NAD(P)H:quinone oxidoreductase 1 gene, NQO1, contains a C to T transition at amino acid codon 187, which results in very low enzymatic activity. Previous studies of the association between NQO1 genotype and lung cancer have had mixed findings. This population-based case control study examines the association between NQO1 genotype and lung cancer in the largest sample of never smokers (<100 cigarettes, lifetime) to date. Cases (n = 161) were identified through the metropolitan Detroit Surveillance, Epidemiology and End Results (SEER) program, and 5-year age- and race-matched population-based controls (n = 173) were identified using random digit dialing. Allele frequencies of C and T, respectively, were 0.79 and 0.21 in Caucasians, and 0.84 and 0.16 in African Americans. Among those diagnosed aged >/=50 years, C/T and T/T genotyped individuals had 0.48 times lower lung cancer risk than individuals with C/C genotype (95% CI: 0.27-0.87). There was a non-significant suggestion of a protective effect associated with the T allele among those with a history of environmental tobacco smoke exposure (OR = 0.57, 95% CI: 0.32-1.03) but not among those without (OR = 0.98, 95% CI: 0.41-2.38). Sex, race, family history of lung cancer and histologic type did not modify the effect of NQO1 genotype on lung cancer risk. The observed risk reductions may be attributable to the greatly reduced procarcinogen activating of NAD(P)H:quinone oxidoreductase 1 in individuals with at least one copy of the T allele.

A major lung cancer susceptibility locus maps to chromosome 6q23-25

Lung cancer is a major cause of death in the United States and other countries. The risk of lung cancer is greatly increased by cigarette smoking and by certain occupational exposures, but familial factors also clearly play a major role. To identify susceptibility genes for familial lung cancer, we conducted a genomewide linkage analysis of 52 extended pedigrees ascertained through probands with lung cancer who had several first-degree relatives with the same disease. Multipoint linkage analysis, under a simple autosomal dominant model, of all 52 families with three or more individuals affected by lung, throat, or laryngeal cancer, yielded a maximum heterogeneity LOD score (HLOD) of 2.79 at 155 cM on chromosome 6q (marker D6S2436). A subset of 38 pedigrees with four or more affected individuals yielded a multipoint HLOD of 3.47 at 155 cM. Analysis of a further subset of 23 multigenerational pedigrees with five or more affected individuals yielded a multipoint HLOD score of 4.26 at the same position. The 14 families with only three affected relatives yielded negative LOD scores in this region. A predivided samples test for heterogeneity comparing the LOD scores from the 23 multigenerational families with those from the remaining families was significant (P=.007). The 1-HLOD multipoint support interval from the multigenerational families extends from C6S1848 at 146 cM to 164 cM near D6S1035, overlapping a genomic region that is deleted in sporadic lung cancers as well as numerous other cancer types. Parametric linkage and variance-components analysis that incorporated effects of age and personal smoking also supported linkage in this region, but with somewhat diminished support. These results localize a major susceptibility locus influencing lung cancer risk to 6q23-25.

Conditional median survival of patients with advanced carcinoma: surveillance, epidemiology, and end results data

BACKGROUND

Conditional survival is clinically useful, particularly for patients with malignant disease who have a poor prognosis. However, there are no published data on the conditional median survival of patients with advanced carcinoma on a population basis.

METHODS

Data on 217,573 patients with breast, colorectal, lung, or prostate carcinoma who were newly diagnosed with distant disease between 1973 and 1995 and who were followed through the end of 1997 were extracted from the Surveillance, Epidemiology, and End Results (SEER) data base of the National Cancer Institute. The Kaplan-Meier method was employed to estimate conditional median survival and 95% confidence intervals at 0-5 years after the initial diagnosis.

RESULTS

The conditional median survival increased as time elapsed after the initial diagnosis. The increase was slowest and almost leveled off among patients with prostate carcinoma. The median survival of patients with breast carcinoma increased relatively linearly with time, i.e., 5-6 months per year. Conversely, there was a rapid increase in the conditional median survival according to the amount of time since diagnosis for patients with lung and colorectal carcinoma. The trend was most pronounced for patients with colorectal carcinoma. At 5 years after the initial diagnosis, the remaining median survival was longest for patients with colorectal carcinoma, almost 6 years (71.5 months), followed by patients with lung carcinoma (52.5 months), breast carcinoma (42.5 months), and prostate carcinoma (34.5 months). Although race was a correlate with initial survival, gender and age had more impact on late conditional survival.

CONCLUSIONS

The conditional median survival provides useful and encouraging information for patients who survive with advanced disease and for healthcare professionals who treat these patients. However, the information should be used carefully, taking the limitations of these data into account.

Diagnostic radiation and the risk of multiple myeloma (United States)

OBJECTIVE

To evaluate the relationship between cumulative lifetime exposure to diagnostic radiation and the risk of multiple myeloma using data from a large, multi-center, population-based case-control study.

METHODS

Study subjects included a total of 540 cases with newly diagnosed multiple myeloma and 1998 frequency-matched population controls living in three areas of the United States (Georgia, Michigan, New Jersey). Information on exposure to diagnostic X-rays was obtained by personal interview.

RESULTS

No association was found between case-control status and the total number of reported diagnostic X-rays of any type (odds ratio (OR) for 20 or more compared to less than 5 X-rays = 0.9, 95% confidence interval (95% CI) = 0.7-1.2). There was no evidence of an excess risk of multiple myeloma among individuals who reported exposure to 10 or more diagnostic X-rays that impart a relatively high radiation dose to the bone marrow, as compared to individuals reporting no such exposures (OR 0.7, 95% CI 0.4-1.3).

CONCLUSIONS

These data suggest that exposure to diagnostic X-rays has a negligible impact, if any, on risk of developing multiple myeloma.

Suppression of 12-O-tetradecanoylphorbol-13-acetate-induced epidermal hyperplasia and inflammation by the dehydroepiandrosterone analog 16alpha-fluoro-5-androsten-17-one and its reversal by NADPH liposomes

Dehydroepiandrosterone and related steroids produce cancer-preventive and other potentially important therapeutic effects in laboratory animals. These steroids are potent uncompetitive inhibitors of mammalian glucose-6-phosphate dehydrogenase, the first enzyme in the pentose phosphate pathway. Inhibition of this pathway could have profound effects on the supply of 5-carbon sugars required for nucleic acid synthesis as well as on the availability of nicotinamide adenine dinucleotide phosphate (NADPH) and the cellular redox state. NADPH is a source of reducing equivalents for the production of oxygen free radicals, which act as intermediate messengers stimulating mitogenesis and up-regulating the inflammatory response. Using a mixture of NADPH and cationic liposomes to facilitate uptake of the normally impenetrable dinucleotide, we found that intradermal injections of NADPH-liposomes reversed the anti-inflammatory and anti-hyperplastic effects of the dehydroepiandrosterone analog, 16alpha-fluoro-5-androsten-17-one, in mouse skin treated with 12-O-tetradecanoylphorbol-13-acetate, whereas similar treatment had no apparent effect on the anti-hyperplastic and anti-inflammatory effect of corticosterone.

[Clinical diagnosis of acute aortic dissection]

Despite the availability of modern imaging technology, 35% of aortic dissections remain undiagnosed in vivo because clinical criteria for aortic dissection are not available to date. The present study analyzed 250 patients with acute chest and/or back pain, absence of an established differential diagnosis of the pain syndrome and clinical suspicion of acute aortic dissection for presence of 26 clinical variables. Multivariate analysis identified an aortic pain syndrome with immediate onset and/or tearing or ripping character (P < 0.0001), mediastinal and/or aortic widening on chest radiography (P < 0.0002) and pulse- and/or blood pressure differentials (P < 0.0001) as predictors of acute aortic dissection. Probability of dissection was low (7%) with absence of all three variables, intermediate (31 and 39%, respectively) with isolated findings of "aortic pain" or "mediastinal widening", and high (> 83%) with either isolated "pulse- and/or blood pressure differentials" or any combination of the three variables. This model appears useful to improve selection of patients for emergency imaging of the thoracic aorta.

Familial risk of pancreatic cancer

BACKGROUND

Pancreatic cancer is the fifth leading cause of cancer-related mortality in the United STATES: Although smoking and age are known risk factors for pancreatic cancer, several case reports and case-control studies have suggested that there is also a familial risk. We evaluated whether a family history of pancreatic cancer increases the risk of pancreatic cancer in first-degree relatives and whether smoking and younger age at cancer diagnosis further increase this risk.

METHODS

We conducted in-person interviews with 247 patients ("case probands") with pancreatic cancer and 420 population-based control probands to collect risk factor data and pancreatic cancer family history for 1816 first-degree relatives of the case probands and 3157 first-degree relatives of the control probands. We analyzed the data by unconditional logistic regression models, with adjustment for correlated data by use of generalized estimating equations. All statistical tests were two-sided.

RESULTS

A positive family history of pancreatic cancer (i.e., being related to a case proband) or ever-smoking cigarettes approximately doubled the risk of pancreatic cancer (relative risk [RR] = 2.49; 95% confidence interval [CI] = 1.32 to 4.69; RR = 2.04; 95% CI = 1.09 to 3.83, respectively). The RR increased to 8.23 (95% CI = 2.18 to 31.07) for relatives who ever smoked and were related to a case proband who was diagnosed before age 60 years.

CONCLUSION

Routine questioning of patients about a family history of pancreatic cancer, the age of onset of this cancer in their relatives, and the patient's smoking status may identify individuals at high risk of pancreatic cancer. Future research exploring the genetic and environmental interactions associated with the risk of pancreatic cancer is critically important.

Diet and nutrition as risk factors for multiple myeloma among blacks and whites in the United States

OBJECTIVES

To explore whether dietary factors contribute to the risk of multiple myeloma and the two-fold higher incidence among blacks compared to whites in the United States.

METHODS

Data from a food-frequency questionnaire were analyzed for 346 white and 193 black subjects with multiple myeloma, and 1086 white and 903 black controls who participated in a population-based case-control study of multiple myeloma in three areas of the United States.

RESULTS

Elevated risks were associated with obese vs. normal weight (OR = 1.9, 95% confidence interval (CI) = 1.2-3.1 for whites and OR = 1.5, 95% CI = 0.9-2.4 for blacks), while the frequency of obesity was greater for black than white controls. Reduced risks were related to frequent intake of cruciferous vegetables (OR = 0.7, 95% CI = 0.6-0.99) and fish (OR = 0.7, 95% CI = 0.5-0.9) in both races combined, and to vitamin C supplements in whites (OR = 0.6, 95% CI = 0.5-0.9) and blacks (OR = 0.8, 95% CI = 0.5-1.4), with the frequency of vitamin supplement use being greater for white than black controls. However, frequent intake of vitamin C from food and supplements combined was associated with a protective effect in whites (OR = 0.6, 95% CI = 0.4-0.9), but not blacks (OR = 1.2, 95% CI = 0.8-2.1).

CONCLUSIONS

The greater use of vitamin C supplements by whites and the higher frequency of obesity among blacks may explain part of the higher incidence of multiple myeloma among blacks compared to whites in the United States. In addition, the increasing prevalence of obesity may have contributed to the upward trend in the incidence of multiple myeloma during recent decades.

Occupational exposure to pesticides and pancreatic cancer

BACKGROUND

An increased risk of exposure to pesticides for pancreatic cancer has been suggested in a number of epidemiologic studies.

METHODS

Cases (N = 484), aged 30-79 years, were diagnosed in 1986-1989. Controls (N = 2,095) were a random sample of the general population. Information on usual occupation and potential confounding factors was obtained. A job-exposure matrix (JEM) approach was used to estimate the level of occupational exposure to pesticides.

RESULTS

A significant trend in risk with increasing exposure level of pesticides was observed, with ORs of 1.3 and 1.4 for low and moderate/high exposure levels, respectively. Excess risks were found for occupational exposure to fungicides (OR = 1.5) and herbicides (OR = 1.6) in the moderate/high level after adjustment for potential confounding factors. An increased risk for insecticide exposure was disappeared after adjustment for fungicide and herbicide exposures. Results of our occupation-based analysis were consistent with those from the JEM-based analysis.

CONCLUSIONS

Our results suggest that pesticides may increase risk of pancreatic cancer, and indicate the need for investigations that can evaluate risk by specific chemical exposures. Published 2001 Wiley-Liss, Inc.

Clinical prediction of acute aortic dissection

BACKGROUND

Clinical criteria for aortic dissection are poorly defined. Thus, 35% of aortic dissections remain unsuspected in vivo, and 99% of suspected cases can be refuted.

OBJECTIVE

To identify independent predictors of acute aortic dissection and create a prediction model for facilitated estimation of the individual risk of dissection.

METHODS

Two hundred fifty patients with acute chest pain, back pain, or both; absence of an established differential diagnosis of the pain syndrome; and clinical suspicion of acute aortic dissection were evaluated for the presence of 26 clinical variables in a prospective, observational study. Multivariate analysis was performed to create a prediction model of aortic dissection.

RESULTS

Aortic pain with immediate onset, a tearing or ripping character, or both; mediastinal widening, aortic widening, or both on chest radiography; and pulse differentials, blood pressure differentials, or both (P<.001 for all) were identified as independent predictors of acute aortic dissection. Probability of dissection was low with absence of all 3 variables (7%), intermediate with isolated findings of aortic pain or mediastinal widening (31% and 39%, respectively), and high with isolated pulse or blood pressure differentials or any combination of the 3 variables (> or = 83%). Accordingly, 4% of all dissections were assigned to the low-probability group, 19% to the intermediate-probability group, and 77% to the high-probability group of aortic dissection.

CONCLUSIONS

Assessment of 3 clinical variables permitted identification of 96% of the acute aortic dissections and stratification into high-, intermediate-, and low-probability groupings of disease. With better selection for prompt diagnostic imaging, this prediction model can be used as an aid to improve patient care in aortic dissection. Arch Intern Med. 2000;160:2977-2982

Socioeconomic status and multiple myeloma among US blacks and whites

OBJECTIVES

This study examined the relation between socioeconomic status (SES) and risk of multiple myeloma among Blacks and Whites in the United States.

METHODS

This population-based case-control study included 573 cases (206 Blacks and 367 Whites) with new diagnoses of multiple myeloma identified between August 1, 1986, and April 30, 1989, and 2131 controls (967 Blacks and 1164 Whites) from 3 US geographic areas. Information on occupation, income, and education was obtained by personal interview.

RESULTS

Inverse gradients in risk were associated with occupation-based SES, income, and education. Risks were significantly elevated for subjects in the lowest categories of occupation-based SES (odds ratio [OR] = 1.71, 95% confidence interval [CI] = 1.16, 2.53), education (OR = 1.36, 95% CI = 1.06, 1.75), and income (OR = 1.43, 95% CI = 1.05, 1.93). Occupation-based low SES accounted for 37% of multiple myeloma in Blacks and 17% in Whites, as well as 49% of the excess incidence in Blacks. Low education and low income accounted for 17% and 28% of the excess incidence in Blacks, respectively.

CONCLUSIONS

Our results indicate that the measured SES-related factors account for a substantial amount of the Black-White differential in multiple myeloma incidence.

Genetic analysis of families with nonsmoking lung cancer probands

As part of a genetic epidemiologic study of lung cancer among nonsmokers, we investigated the role of genetic predisposition in familial aggregation. Cases were identified from the Metropolitan Detroit Cancer Surveillance System. Information on lung cancer occurrence, smoking habits (active or passive), and chronic respiratory diseases in first-degree relatives was obtained for 257 nonsmoking lung cancer probands (71 males, 186 females) diagnosed at ages 40-84 years. Among the 2,021 first-degree relatives, 24 (2.6%) males and 10 (1.1%) females were reported as having lung cancer. The occurrence of lung cancer among smoking and nonsmoking relatives was 4.5% and 1.1% in males and 2.8% and 0.4% in females, respectively. To evaluate the role of a putative Mendelian gene (one locus, two alleles) in the presence of other risk factors, we performed complex segregation analyses on the data using two different regressive model approaches [Segregation Analysis of a Discrete Trait Under a Class A Regressive Logistic Model, V4.0 (REGD) and Segregation Analysis of a Truncated Trait, V2.0, Model 1(REGTL)] as implemented in the Statistical Analysis for Genetic Epidemiology (SAGE) program. Using either approach, an environmental model best explained the observed lung cancer aggregation in families ascertained through nonsmoking probands. Based on our final model, only 0.04% of this population had a very high risk and 4.2% had a moderate risk of lung cancer. The rest of the population had virtually no risk of lung cancer during their lifetime unless they have multiple risk factors. Among the high-risk individuals without any risk factor under study, the estimated risks at ages 40, 60, and 80 years in males were 16.7%, 83.6%, and 95.4%, and in females were 14.0%, 72.2%, and 88.0%, respectively. Among at-moderate-risk smokers the estimated risks at the same age and gender groups were essentially the same as in the high-risk nonsmokers. Our results suggest that the pattern of lung cancer occurrence in families of nonsmoking lung cancer patients differs from that in families of smoking lung cancer patients. Despite the profound effect of smoking on the risk of lung cancer, other environmental and/or genetic risk factors need to be identified.

Increased cancer risk among relatives of nonsmoking lung cancer cases

Lung cancer has been shown to aggregate in families of nonsmoking lung cancer cases with an earlier age at onset. The current study evaluates whether relatives of nonsmoking lung cancer cases are at increased risk of cancers at sites other than lung. Families were identified through 257 population-based, nonsmoking lung cancer cases and 277 population-based, nonsmoking controls residing in metropolitan Detroit. Data were collected for 2,252 relatives of cases and 2,408 relatives of controls. First-degree relatives of nonsmoking lung cancer cases were at 1.52-fold (95% CI, 1.02-2.27) increased risk of cancer of the digestive system after adjustment for each relative's age, race, sex, and smoking status. Relative risk estimates also were elevated, but not significantly, for tobacco-related cancers (RR = 1.39) and breast cancer (RR = 1.72). Among first-degree relatives of younger probands (age 40-59), risk was non-significantly increased 72% (95% CI 0.95-3.10) for all cancers combined and 3.14-fold for cancers of the digestive system (95% CI 0.76-12.9). Nonsmoking relatives of cases were at increased risk of all cancer sites combined (RR = 1.32; 95% CI 1.003-1.73), cancers other than lung (RR = 1.37; 95% CI 1.03-1.82), and digestive system cancers (RR = 2.01; 95% CI 1.20-3.37). These findings of moderate familial aggregation for cancers of the lung, digestive system, breast, and tobacco-related sites suggest that common susceptibility genes may act to increase risk for a variety of cancers in families.

Sexual behaviour, STDs and risks for prostate cancer

A population-based case-control study was carried out among 981 men (479 black, 502 white) with pathologically confirmed prostate cancer and 1315 controls (594 black, 721 white). In-person interviews elicited information on sexual behaviour and other potential risk factors for prostate cancer. Blood was drawn for serologic studies in a subset of the cases (n = 276) and controls (n = 295). Prostate cancer risk was increased among men who reported a history of gonorrhoea or syphilis (odds ratio (OR) = 1.6; 95% confidence internal (CI) 1.2-2.1) or showed serological evidence of syphilis (MHA-TP) (OR = 1.8; 95% CI 1.0-3.5). Patterns of risk for gonorrhoea and syphilis were similar for blacks (OR = 1.7; 95% CI 1.2-2.2) and whites (OR = 1.6; 95% CI 0.8-3.2). Risks increased with increasing occurrences of gonorrhoea, rising to OR = 3.3 (95% CI 1.4-7.8) among subjects with three or more events (Ptrend = 0.0005). Frequent sexual encounters with prostitutes and failure to use condoms were also associated with increased risk. Syphilis, gonorrhoea, sex with prostitutes and unprotected sexual intercourse may be indicators of contact with a sexually transmissible factor that increases the risk of prostate cancer.

Lung cancer risk in families of nonsmoking probands: heterogeneity by age at diagnosis

In an earlier investigation, we did not detect a major genetic component to lung cancer in families of nonsmoking lung cancer probands. However, heterogeneity with respect to familial aggregation, based on probands' age at diagnosis, was evident. We reanalyzed our previously collected data of 257 families, stratified by age at diagnosis of the probands, using complex segregation analysis. We specifically tested the effects of a Mendelian diallelic gene, history of tobacco use, and history of selected chronic lung diseases in families with a proband diagnosed at the age of 60 years or older and in families with a younger proband (i.e. , under 60 years of age). Cases were identified from the Metropolitan Detroit Cancer Surveillance System. Information on lung cancer occurrence, smoking history, and chronic respiratory diseases in first-degree relatives was obtained for 210 older probands and for 47 younger probands. In older probands' families, no evidence of a major genetic effect was detected. A history of emphysema and tobacco-smoke exposure were found to be significant risk factors. In younger probands' families, a Mendelian codominant model with significant modifying effects of smoking and chronic bronchitis best explained the observed data. Our results suggest the presence of a high-risk gene contributing to early-onset lung cancer in a population where the probands are nonsmokers.