Trends in the incidence of testicular germ cell cancer in Ontario by histologic subgroup, 1964-1996

BACKGROUND: Testicular cancer is rare but is notable because it affects mainly young men. The incidence of this disease has been increasing in developed countries throughout the world for several decades. The authors examined trends in the incidence of testicular germ cell cancer in Ontario for the period 1964-1996 according to the 2 main histologic groups, seminoma and non-seminoma. METHODS: Data on incident cases of testicular germ cell cancer diagnosed in Ontario residents aged 15-59 years between 1964 and 1996 were extracted from the population-based Ontario Cancer Registry. Annual rates of testicular cancer for the 2 histologic groups were analysed by means of log-linear regression to estimate average annual percent change. RESULTS: Between 1964 and 1996 the incidence of testicular germ cell cancer increased by 59.4%, from 4.01 to 6.39 per 100,000. This corresponded to an average annual increase of about 2% for both nonseminoma and seminoma. The relative increase in incidence was greatest in the lowest age group (15-29 years) for both histologic groups, although the data suggest that the incidence of nonseminoma cancer in this age group began to decline in the early 1990s. The increase in incidence appears to be due to a birth cohort effect, with more recent cohorts of men at increased risk. INTERPRETATION: The rise in the incidence of testicular germ cell cancer, not only in Ontario but also in many developed countries, requires investigation. The search for explanatory factors should focus on exposures whose prevalence may have increased over the past few decades and that are common enough to affect population incidence. The similarity of trends for seminoma and nonseminoma cancer suggests that the underlying risk factors are likely the same.     

Survival after a diagnosis of testicular germ cell cancers in Germany and the United States, 2002–2006: A high resolution study by histology and age

Introduction: The aim of this study was to provide detailed age-specific (5-year age groups) and histology-specific (histologic subtypes of seminoma and nonseminoma) relative survival estimates of testicular germ cell cancer patients in Germany and the United States (U.S.) for the years 2002–2006 and to compare these estimates between countries. Methods: We pooled data from 11 cancer registries of Germany and used data from the U.S. (SEER-13 database) including 11,508 and 10,774 newly diagnosed cases (1997–2006) in Germany and the U.S., respectively. We estimated 5-year relative survival (5-year-RS) by histology and age based on period analysis. Results: 5-year-RS for testicular germ cell tumors was 96.7% and 96.3% in Germany and the U.S., respectively. 5-Year-RS for spermatocytic seminoma was close to 100% in both countries. 5-Year-RS for nonseminoma was lower than for classical seminoma in Germany (93.3% versus 97.6%) and the U.S. (91.0% versus 98.2%). Among nonseminomas, choriocarcinomas provided the lowest 5-year-RS in both countries (Germany 80.1%, U.S. 79.6%). Age-specific 5-year-RS for seminoma showed only little variation by age. 5-Year-RS for nonseminomas tended to be lower at higher ages, especially for malignant teratoma. Discussion: This is the first study that provides up-to-date survival estimates for testicular cancer by histology and age in Germany and the U.S. Survival after a diagnosis of testicular cancer is very comparable between Germany and the U.S. 5-Year-RS for spermatocytic seminoma was close to 100% and the lowest 5-year-RS occurred among choriocarcinoma. Higher age at diagnosis is associated with a poorer prognosis among nonseminoma patients.     

Bilateral germ cell testicular tumors

PURPOSE: To study the clinical characteristics of bilateral testicular tumors in the cisplatin era. PATIENTS AND METHODS: Between November 1988 and November 1998 2386 testicular cancer patients were treated in our Department and 72 bilateral germ cell testicular cancer patients were retrospectively explored (3%). The incidence, the clinical and histological characteristics and, in the case of asynchronous tumor, the interval between the two tumors were analyzed. RESULTS: During the 10 years 19 synchronous (26.4%) and 53 asynchronous bilateral germ cell testicular cancers (73.6%) were treated. The incidence of bilateral synchronous seminoma was 68.4%. Among the asynchronous tumors 9 concordant seminomas and 9 concordant nonseminomas were detected. In the first, second and third 5-year follow-up period 39.6, 30.2, and 28.2% of asynchronous tumors were diagnosed. The incidence of seminoma after the first castration in the 5, 10 and 15 years was 19, 37.5, and 60%, respectively. The overall survival rates of synchronous and asynchronous testicular cancer were 84 and 93%. In cases of asynchronous tumor the prevalence of stage I cancer was significantly greater in a regularly controlled population (p=0.014) than in the not regularly followed population, but the survival rate was good in both groups. Nonseminoma showed up earlier as first and second tumor than seminoma (p=0.05, p=0.045). The interval between the two asynchronous tumors was shorter in the case of nonseminoma than in the case of seminoma (p=0.002). CONCLUSION: The prognosis of bilateral germ cell testicular cancer is good because of the high incidence rate of seminoma and the effective treatment. With regular follow-up the early diagnosis of second testicular tumors is probable. The interval between the tumors depends on the patients' age and the histology of the second tumor, in the case of seminoma it is longer. The effect of the previous treatment on the incidence of seminoma and the interval between the two asynchronous tumors requires further investigations.     

Prolactin secretion in testicular cancer patients

The role of prolactin (PRL) in testicular function and in its disorders is still obscure. To draw some preliminary conclusions on the relation between the PRL and testis cancer, we assessed the PRL response to thyrotropin-releasing hormone (THR) in 15 patients with testicular cancer (8 seminoma; 6 nonseminoma; 1 leydigioma), and in 11 healthy male subjects as controls. The results showed that 5/15 cancer patients gave no PRL response to TRH; 4 of them had a nonseminoma and the fifth a seminomatous testis carcinoma. Patients with nonseminoma had significantly lower mean peak values of PRL after TRH than controls or patients with seminoma. The biological significance of the altered PRL response to TRH in testicular carcinoma has still to be established.     

Retroperitoneal and metachronous testicular germ cell tumors with different histology and teratoma growing syndrome--a case report

It is presented a case of a 32-year-old male with the three primary tumors diagnosed within a time period of 3 years; retroperitoneal nonseminoma in 2002, retroperitoneal mature teratoma in 2004, and metachronous testicular seminoma in 2005. We discuss the unusual presentation of these three rare events occurring in the same patient without known risk factors.     

Genetic variants in the 8q24 locus and risk of testicular germ cell tumors

Much evidence supports the premise that population genetic variation contributes significantly to the risk of testicular germ-cell tumor (TGCT). However, investigations of the association between genomic markers and TGCT susceptibility are scarce. Single nucleotide polymorphisms (SNPs) at the locus 8q24 have recently been found to be associated with prostate, colorectal and breast cancer. The US Servicemen’s testicular tumor environmental and endocrine determinants (STEED) study was used to investigate the association of 15 specific 8q24 SNPs with TGCT and its two main histologic groups of seminoma and nonseminoma. Conditional and unconditional logistic regression models, adjusted for the matching variables of year of birth, race/ethnicity and serum date, were utilized to produce odds ratios (OR) and 95% confidence intervals (95%CI). The analysis included 680 controls and 568 TGCT cases. In the TGCT analysis, no SNP was associated with risk in both heterozygotes and variant homozygotes. When stratified by histology the seminoma analysis also showed no association with the 8q24 SNPs. Conversely, the analysis of nonseminomas had three tentative associations (rs6470494, OR_{genotype AG} = 1.15, 95%CI: 0.86–1.54; OR_{genotype GG} = 1.68, 95%CI: 1.04–2.73; p for trend = 0.04) (rs13254738, OR_{genotype GT} = 1.04, 95%CI: 0.77–1.40; OR_{genotype TT} = 1.62, 95%CI: 1.06–2.49; p for trend = 0.07) (rs10505476, OR_{genotype CT} = 0.67, 95%CI: 0.50, 0.91; OR_{genotype TT} = 0.81, 95%CI: 0.47–1.39; p for trend = 0.04). There was no linkage disequilibrium between any of the 8q24 SNPs analyzed in this population. In conclusion, this study has found little evidence for an association between the reported 8q24 SNPs and TGCTs, although the findings for nonseminoma may be worth further investigation.     

Évolution du cancer du testicule en France

As in many countries, the mortality rate of testicular cancer in France has decreased from 0.75 in 1978 to 0.25 per 100,000 in 2000 (standardized on world population). Over the same period, the incidence rate increased from 3.17 in 1978 to 4.82 per 100,000 in 2000 (standardized on world population). However, although the incidence of seminoma has increased continually with all birth cohorts, the incidence of non-seminomas first decreased for the men born between the first and second world wars and then increased at the same rate as the seminoma rate. No explanation for this pattern has yet been provided, but it does not appear to be simply an artefact. A North/South and East/West gradient has been observed, as the incidence varies from 4.0 in the South West to 8.0 in the North East. There is an estimated 1,500 new cases of testicular cancer each year in France, including 960 new cases for men between the ages of 15 and 40.     

Those ubiquitous fertility trends: United States, 1945-1979

1970-79 US fertility trends among differnet racial, regional, age, educational, parity, and socioeconomic subgroups in the population were examined, using own children data from the 1976 Survey of Income and Education (SIE) and the March Current Population Surveys (CPS) from 1968-80. In addition, cross-sectional differences in fertility for the subgroups were compared for 1970 and 1976, using multiple regression analysis. 1st, the appropriateness of using fertility rates obtained from own children data was assessed by comparing fertility rates obtained from the SIE data with those derived from vital statistic and census data. The comparative analysis confirmed that the SIE data yielded an accurate estimate of period fertility rates for currently married women, provided the subgroup samples were sufficiently large. CPS fertility estimates were also judged to be accurate if data from 3 adjacent survey years was pooled to increase sample size. Fertility trends for 5 educational groups were assessed separately for 1967-73. During this periold, there was a marked decline in fertility for all 5 groups; for the group with 5-8 years of education the decline was only 14%, but for the other 4 groups, which included women with 9-16 or more years of education, the decline in fertility ranged from 26-29%. In assessing the 1970-76 trends, the sample was restricted to own children, aged 3 years or less, of currently married women, under 40 years of age. Among whites, there was an overall 20% decline in fertility between 1970-76 and an overall fertility increase of about 2% between 1976-79. These trends were observed in all 28 white subgroups. A similar pattern was observed for blacks. There was an overall fertility decline of 24% between 1970-76, and this decline was apparent for all subgroups except women with college degrees. Betwen 1976-79, black fertility rates, unlike white rates, continued to decline, but the rate of decline was only 3%. Furthermore, the decline in almost all the black subgroups was markedly less than in the 1970-76 periold, and for many of the subgroups the trend was reversed and fertility increased. In summary, the fertility trends noted for 1970-79 were pervasive for almost all the subgroups for both blacks and whites; i.e., there was a marked decline in fertility between 1970-76 and than a reversal or slowing down of the decline during the 1976-79 for all black and white subgroups. Cross-sectional fertility differences in the subgroups in 1970 and in 1979 were quite similar, and fertility rates differed markedly for the separate subgroups. These differences do not, of course, explain the pervasive trends observed in the analysis of the fertility rates over time. A similar study assessing fertility trends among subgroups for the early 1940's through the late 1960s also revealed the pervasive nature of period fertility trends. Demographers have not as yet been able to explain these shifts in fertility that cut across all subgroups in the US and which also characterize the period fertility rates in other developed countries. Tables provided information on 1) total fertility rates by educational level and by geographical region for 1945-1975; 2) % change in number of own children less than 3 years of age among women under age 40 by maternal age, maternal education, initial parity, geographical region, and husband's income; and 3) mean number of own children less than 3 years of age among women under age 40 by maternal age, education, parity, region, and husband's income.     

Analysis of trends in cancer mortality in England and Wales during 1951-80 separating changes associated with period of birth and period of death.

Cancer mortality rates in England and Wales were analysed so to describe simultaneously changes affecting successive generations--that is, associated with period of birth--as well as changes associated with the period of which the deaths took place. When mortality from all cancers was considered the analysis implied that, contrary to a widely held view, the rate of death from cancer had been declining in each sex in successive generations. For men the decline had occurred in generations born since 1900, whereas for women the peak came in the 1925 birth group. On the other hand, there had been little decline in the rates associated with period of death. Five examples of cancers of specific organs for which the trends contrasted are shown.     

Time trends in testicular cancer in Croatia 1983-2007: rapid increases in incidence, no declines in mortality

Testicular cancer, although a rare malignancy, represents the most common cancer in young male populations of Western origin. While increasing incidence trends of testicular cancer have been reported, mortality is declining in many high-resource settings. Using national data from the Croatian National Cancer Registry for the period 1983-2007, time trends were analysed by joinpoint regression and Age-Period-Cohort models. The present study is the first to analyse the testicular cancer trends in the Croatian population. Over the 25-year period, a mean number of 89 incident cases and 13 deaths were reported annually. The observed mean annual increases in age-standardised rates were 7.0% for incidence and 1.6% for mortality, with no abrupt linear changes (joinpoints) identified. The incidence rates of testicular cancer incidence have been steeply increasing in successive cohorts born since the mid-1930s. The rapid rise in testicular cancer incidence in the Croatian population appears to be one of the highest rates of increase recorded in Europe and worldwide. The lack of decline in the mortality rates over time, while based on relatively few deaths, highlights a need for improvements in diagnostics and management of therapy in Croatia in order to improve the survival and quality-of-life of testicular cancer patients.     

Cancer mortality among immigrant populations in Ontario, 1969 through 1973.

Ontario is home to a sizeable, recently established immigrant population whose cancer mortality has until now remained unexamined. The province''s six largest immigrant groups (British, Italian, German, Dutch, Polish and Soviet) were investigated to compare their cancer mortality experience with that prevailing in Ontario and in their countries of birth for the period 1969 through 1973. Standardized mortality ratios (SMRs) were computed from data from Statistics Canada and the World Health Organization (for 1971) for five sites of cancer. The rates of death from stomach cancer were significantly higher for the immigrant groups (except the Germans) than for the Canadian-born (SMRs 158.6 to 256.1) and were significantly lower for the immigrants (except the Dutch) than for the populations of their countries of birth (SMRs 26.5 to 72.9). The rates of death from colorectal cancer and cancer of the breast tended to be lower among the immigrants. Most male immigrants had high rates of death from lung cancer relative to the Canadian-born, whereas their female counterparts had relatively low rates. For most of the immigrant groups the rates of death from prostate cancer closely resembled those prevailing in the country of birth. Displacement of cancer mortality experience towards that in Ontario was most evident for Polish immigrants. It may have been too soon to see trends among the more recent immigrants (Italian, German and Dutch), who, for the most part, had not yet reached the age of highest cancer risk. Ontario should provide a valuable resource for further studies of lifestyle and environmental determinants of cancer.     

Visualization of mosaicism in tissues of normal and mismatch-repair-deficient mice carrying a microsatellite-containing transgene

We tested for azoospermia factor (AZF) deletions 17 loci corresponding to AZF subintervals a-d in 17 cases of testicular tumors occurring in Finns. While DNA samples from 48 CEPH and 32 Finnish males showed no deletions, patients with testicular cancer displayed AZF deletion mosaicisms in various non-tumor tissues (13 cases) and specific deletion haplotypes in tumor tissues (10 cases). Two of the cases with AZF deletions were testicular non-Hodgkin lymphomas indicating that Y-microdeletions appear also in malignancies other than seminoma and non-seminoma tumors. In good agreement with this assumption, we detected one AZF deletion in normal cells from 1 of 5 HNPCC cases, heterozygous for an MLH1 mutation. We propose that AZF deletions occur in early embryogenesis due to mutations of TSPY, mismatch repair (MMR), or X-specific genes. Since fathers of testicular, tumor cases did not exhibit AZF deletions, we assumed they were not carriers of the mutation inducing AZF deletion-mosaicisms. Therefore, tumor cases should have received the MMR gene or X mutations via the maternal lineage, or for the case of TSPY and MMR genes via a sperm carrying a mutation occurred in the paternal germ-cell line. We consider AZF microdeletions in non-tumor cells to be part of a broader pattern of chromosome instability producing susceptibility to testicular tumors. Clonal transformation and expansion of one of these tumor-susceptible cell lineages give rise to testicular tumors showing genome anomalies characteristic of testicular cancers (i12p, LOH and genetic imbalance for various autosomal regions, Y- and autosomal MSI, specific AZF deletion haplotypes).     

Breast Cancer at the Ontario Cancer Clinics, 1938-1956: A Statistical Review

In Ontario, breast cancer accounts for one death in every 27 among females. In 1938-1956 some 40% of all new cases were registered at the Ontario Cancer Foundation''s regional clinics. The five-year crude survival rate for 11,393 women was 45.4%, and for 91 men, 36.3%. Survival rates were strongly affected by extent of disease; when this was allowed for, pregnancy and treatment method were also found to influence survival rate. Simple mastectomy with radiotherapy gave results that appeared comparable to those after radical mastectomy, alone or with radiotherapy. There was a 20% improvement in the crude five-year survival rate over the period of the survey. The need for great caution in interpreting these findings is stressed.     

Leading Causes of Death among Asian American Subgroups (2003–2011)

Background

Our current understanding of Asian American mortality patterns has been distorted by the historical aggregation of diverse Asian subgroups on death certificates, masking important differences in the leading causes of death across subgroups. In this analysis, we aim to fill an important knowledge gap in Asian American health by reporting leading causes of mortality by disaggregated Asian American subgroups.

Methods and Findings

We examined national mortality records for the six largest Asian subgroups (Asian Indian, Chinese, Filipino, Japanese, Korean, Vietnamese) and non-Hispanic Whites (NHWs) from 2003-2011, and ranked the leading causes of death. We calculated all-cause and cause-specific age-adjusted rates, temporal trends with annual percent changes, and rate ratios by race/ethnicity and sex. Rankings revealed that as an aggregated group, cancer was the leading cause of death for Asian Americans. When disaggregated, there was notable heterogeneity. Among women, cancer was the leading cause of death for every group except Asian Indians. In men, cancer was the leading cause of death among Chinese, Korean, and Vietnamese men, while heart disease was the leading cause of death among Asian Indians, Filipino and Japanese men. The proportion of death due to heart disease for Asian Indian males was nearly double that of cancer (31% vs. 18%). Temporal trends showed increased mortality of cancer and diabetes in Asian Indians and Vietnamese; increased stroke mortality in Asian Indians; increased suicide mortality in Koreans; and increased mortality from Alzheimer’s disease for all racial/ethnic groups from 2003-2011. All-cause rate ratios revealed that overall mortality is lower in Asian Americans compared to NHWs.

Conclusions

Our findings show heterogeneity in the leading causes of death among Asian American subgroups. Additional research should focus on culturally competent and cost-effective approaches to prevent and treat specific diseases among these growing diverse populations.     

Impact du délai diagnostique sur la survie du cancer du testicule

Objectives

Testicular cancer is the leading cancer of young adults and its incidence is increasing in almost all industrialized countries. The survival rate after testicular cancer is 95%, all stages combined, but a group of patients with poor prognosis still fails to respond to treatment. The time to diagnosis is defined as the time in months between perception of the first symptoms of testicular cancer by the patient and the diagnosis of the disease by the doctor. The objective of this study is to determine whether the time to diagnosis has a prognostic value, particularly whether it is correlated with the stage of the disease and survival.

Material and Methods

The time to diagnosis was studied in 542 patients with a diagnosis of testicular cancer between 1983 and 2002 in the Midi-Pyrenées region. Information concerning the disease and treatments contained in medical files was collected on a summary document. The time to diagnosis was correlated with prognostic parameters, including stage and survival.

Results

The mean time to diagnosis was 3.7±5.1 months and was longer for seminomas (4.9±6.1 months) than for non-seminomatous germ cell tumours (NSGCT) (2.8 ±4.0 months). The time to diagnosis was correlated with the stage of the disease and the 5-year survival on the overall population and in the NSGCT group, but not in the seminoma group.

Conclusions

Early diagnosis has a prognostic value (correlation with stage of the disease and 5-year survival rate). Testicular cancer information campaigns should therefore be envisaged.     

Cancer of the Breast in Ontario

The breast is the leading cancer site among women; it accounts for 20% of all female cancer deaths. The lifetime probability of death from breast cancer for a female born in Ontario is 3.3%; that is, one in every 30 women will die of breast cancer. The risk of developing breast cancer is almost twice this figure.The medical certificate of death yields a reliable estimate of the number of persons who die of breast cancer, and the level of the age-specific breast cancer death rates has not changed over the past 30 years. Cohort analysis yields an indistinguishable mortality pattern for succeeding cohorts of women from 1871. Available information indicates no change in incidence.The stable mortality and incidence rates suggest that there has been little or no change in the survival rate, despite emphasis on early diagnosis and improvement in therapeutic skills and in technical facilities.     

A Statistical Review of Malignant Testicular Tumours Based on the Experience of the Ontario Cancer Foundation Clinics, 1938-1961

For the 827 patients with malignant testicular tumours registered at the Ontario Cancer Foundation''s regional clinics in the period 1938-1961, the probability of surviving for five years after treatment was 59.8%; for the 731 patients who received all or part of their initial treatment at the clinics or were not treated anywhere, five-year survival probability was 62.7%. Most deaths from testicular cancer took place in the first two years after treatment, and 90% of recorded recurrences were diagnosed before the third anniversary. Survival rates were strongly influenced by histological type and extent of disease, and to some degree by age. Survival did not seem to be closely correlated with delay after first symptom, site or size of primary lesion, ectopia, surgical treatment of the abdominal nodes, site or dosage of radiation, or chemotherapy. The survival rates in this series of cases compare favourably with those of other large series.     

Coronary artery bypass grafting in Canada: national and provincial mortality trends, 1992-1995

BACKGROUND: Despite a body of research on outcomes of coronary artery bypass grafting (CABG) in Canada, little is known about Canada-wide outcome trends and interregional differences in outcome. The objectives of this study were to examine Canadian trends in rates of in-hospital death after CABG and to compare provincial risk-adjusted death rates. METHODS: Hospital discharge data were obtained from the Canadian Institute for Health Information and were used to identify complete cohorts of patients who underwent CABG in 8 provinces in fiscal years 1992/93 through 1995/96. Data from Quebec hospitals were not available. A logistic regression model was used to calculate risk-adjusted death rates by year, province, and province and year. RESULTS: A total of 50,357 CABG cases were studied, with an overall death rate of 3.6%. A national trend of decreasing mortality was found, with a risk-adjusted death rate of 3.8% in 1992/93 versus 3.2% in 1995/96 (relative decrease of 17%) (p < 0.001 for difference across years). Some provinces (e.g., Alberta, Manitoba and Ontario) achieved overall declines in death rates over the study period, whereas others (e.g., British Columbia and Saskatchewan) did not. The average severity of illness of patients who underwent CABG differed considerably across provinces. Despite risk adjustment for these differences, provincial death rates varied significantly (p < 0.001). INTERPRETATION: Rates of death after CABG in Canada decreased significantly in a relatively short period. Despite this encouraging finding, there were interprovincial differences in severity of illness and risk-adjusted death rates. This finding raises the possibility of unequal access to CABG and variable quality of care for patients undergoing the surgery across Canadian provinces.     

Recent time-trends of age-specific death rates for breast cancer: Quebec and other provinces, 1965 through 1974.

For the 10-year period 1965 through 1974 the age-specific death rates for cancer of the breast decreased among middle-aged women, especially at ages 40 to 49 years, in Quebec, the Maritimes and the Prairies but not in Ontario or British Columbia. In women under 35 years of age the mortality generally increased, while in women aged 60 to 64 years there was little change except in the Prairies, where the rate increased. It seems probable that the trends reflect changes in incidence rather than in case-fatality. Some, but not all, of the pattern could be explained by changes in fertility over the past 50 years.     

Is perinatal care in southwestern Ontario regionalized?

OBJECTIVE: To determine whether perinatal care in southwestern Ontario is regionalized, to identify trends over time in referral patterns, to quantify trends in perinatal death rates and to identify trends in perinatal death rates that give evidence of regionalization. DESIGN: Cohort study. SETTING: Thirty-two hospitals in southwestern Ontario (1 level III, 1 modified level III and 30 level II or I). PATIENTS: All pregnant women admitted to the hospitals and their infants. MAIN OUTCOME MEASURES: Antenatal and neonatal transfer status, live-born with discharge home alive from hospital of birth, stillborn, and live-born with death before discharge. RESULTS: Between 1982 and 1985 the antenatal transfer rate increased from 2.2% to 2.8% (p less than 0.003). The proportion of births of infants weighing 500 to 1499 g increased from 49% to 69% at the level III hospital. The neonatal transfer rate increased from 26.2% to 47.9% (p less than 0.05) for infants in this birth-weight category and decreased from 10.2% to 7.1% (p less than 0.03) for infants weighing 1500 to 2499 g. The death rate among infants of low birth weight was lowest among those born at the level III centre and decreased at all centres between 1982 and 1985. CONCLUSIONS: Perinatal care in southwestern Ontario is regionalized and not centralized; regionalization in southwestern Ontario increased between 1982 and 1985.