Age-period-cohort modelling of large-bowel-cancer incidence by anatomic sub-site and sex in Denmark

Risk factors for colorectal cancer significantly vary by anatomic site

Objective

To conduct an anatomic site-specific case–control study of candidate colorectal cancer (CRC) risk factors.

Design

Case–control study of US veterans with >1 colonoscopy during 1999–2011. Cases had cancer registry-identified CRC at colonoscopy, while controls were CRC free at colonoscopy and within 3 years of colonoscopy. Primary outcome was CRC, stratified by anatomic site: proximal, distal, or rectal. Candidate risk factors included age, sex, race/ethnicity, body mass index, height, diabetes, smoking status, and aspirin exposure summarised by adjusted ORs and 95% CIs.

Results

21 744 CRC cases (n=7017 rectal; n=7039 distal; n=7688 proximal) and 612 646 controls were included. Males had significantly higher odds relative to females for rectal cancer (OR=2.84, 95% CI 2.25 to 3.58) than distal cancer (OR=1.84, 95% CI 1.50 to 2.24). Relative to whites, blacks had significantly lower rectal cancer odds (OR=0.88, 95% CI 0.82 to 0.95), but increased distal (OR=1.27, 95% CI 1.19 to 1.37) and proximal odds (OR=1.62, 95% CI 1.52 to 1.72). Diabetes prevalence was more strongly associated with proximal (OR=1.29, 95% CI 1.22 to 1.36) than distal (OR=1.15, 95% CI 1.08 to 1.22) or rectal cancer (OR=1.12, 95% CI 1.06 to 1.19). Current smoking was more strongly associated with rectal cancer (OR=1.81, 95% CI 1.68 to 1.95) than proximal cancer (OR=1.53, 95% CI 1.43 to 1.65) or distal cancer (OR=1.46, 95% CI 1.35 to 1.57) compared with never smoking. Aspirin use was significantly more strongly associated with reduced rectal cancer odds (OR=0.71, 95% CI 0.67 to 0.76) than distal (OR=0.85, 95% CI 0.81 to 0.90) or proximal (OR=0.91, 95% CI 0.86 to 0.95).

Conclusion

Candidate CRC risk factor associations vary significantly by anatomic site. Accounting for site may enable better insights into CRC pathogenesis and cancer control strategies.

Colon cancer in Iceland--a nationwide comparative study on various pathology parameters with respect to right and left tumor location and patients age

Increasing evidence suggests genetic, biological and demographical difference between right and left colon cancer. Studies have also indicated age differences in the pathology of colon cancer. There is a scarcity of large-scale studies that closely examine the pathological differences regarding age and tumor location. The aim of our study was to do an extensive comparison of right- and left- sided colon cancers as well as comparing patients <50 years with older patients. A retrospective, population-based study was carried out on all patients with colon cancer in Iceland between 1955 and 2004. A total of 2293 cases were analyzed (1148 men, 1145 women). All histopathology material was re-evaluated. Differences in tumor characteristics between right and left location and younger (<50) and older (≥50) patients was evaluated in particular. Higher TNM-stage, larger tumors, vessel invasion, mucinous type, high grade and expanding tumor border occurred more frequently in right- versus left-sided lesions while annular and polypoid tumors were more common in left-sided tumors (p < 0.05). Young patients had more frequent lymph node metastases, vessel invasion, nonpolypoid lesions and infiltrating tumor border (p < 0.05). Right-sided lesions show more aggressive features, reflected in morphology and stage. Younger patients present more frequently with adverse features than do older patients. Frequency of right- and left-sided colon cancer differs by age with pronounced age-location differences in females. This supports the assumption of differences in etiology and carcinogenesis of right- and left-sided colon cancer, and between young and old patients.

Sex disparities in colorectal cancer incidence by anatomic subsite, race and age

Although incidence of colorectal cancer (CRC) in the United States has declined in recent years, rates remain higher in men than in women and the male-to-female incidence rate ratio (MF IRR) increases progressively across the colon from the cecum to the rectum. Rates among races/ethnicities other than Whites or Blacks have not been frequently reported. To examine CRC rates by sex across anatomic subsite, age and racial/ethnic groups, we used the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) program for cases diagnosed among residents of 13 registries during 1992-2006. Incidence rates were expressed per 100,000 person-years and age-adjusted to the 2000 US Standard Population; MF IRR and 95% confidence intervals were also calculated. Among each racial/ethnic group, the MF IRR increased fairly monotonically from close to unity for cecal cancers to 1.81 (Hispanics) for rectal cancers. MF IRRs increased with age most rapidly for distal colon cancers from <1.0 at ages <50 years to 1.4-1.9 at older ages. The MF IRR for rectal cancers also rose with age from about 1.0 to 2.0. For proximal cancer, the MF IRR was consistently <1.5; among American Indian/Alaska Natives, it was <1.0 across all ages. The MF IRRs for CRC vary markedly according to subsite and age but less by racial/ethnic group. These findings may partially reflect differences in screening experiences and access to medical care but also suggest that etiologic factors may be playing a role.

Trends in colorectal cancer incidence in Norway 1962-2006: an interpretation of the temporal patterns by anatomic subsite

There have been rapid increases in the incidence of colorectal cancer in Norway since the 1960s, and rates rank among the highest worldwide. The primary objectives are to describe trends in left- and right-sided colon cancer and rectal cancer by calendar period and birth cohort and to generate hypotheses as to the etiological factors in operation. Although the age-adjusted incidence rates of both colon and rectal cancer increased in Norway in both sexes up to the 1980s, subsite- and age-specific analyses reveal a deceleration in the rate of increase thereafter, apparent in the rates of both left-sided colon and rectal cancer. Overall trends in incidence of right-sided colon cancer continue to increase in both sexes. Rates in both left- and right-sided colon cancers have tended to stabilize or decrease among successive generations born after 1950, however, while incidence rates of rectal cancer appear to be increasing in recent generations. The all-ages rates are thus in keeping with the commonly reported "left to right shift" of colon cancer, although standardization masks important observations. The cohort patterns provide further evidence that factors earlier in life are important, and while the complex etiology makes interpretation difficult, modifications in diet, obesity and physical activity in Norway are likely among the drivers of the trends in one or more of the colorectal subsites examined. In summary, the recent downturn in the disease at younger ages provides some reason for optimism, although possible increases in rectal cancer among recent birth cohorts are of concern.

The changing distribution of colorectal cancer in Barbados: 1985-2004

PURPOSE

Recent reports have suggested a shift to the right in older female patients of colon cancer. This is believed to be representative of more accessible national endoscopic screening programs.

METHODS

We report the demographic shift in colorectal cancer based on an analysis of resection specimens during four five-year time periods from 1985 to 2004 at the University Hospital, Barbados. Differences in population-based colorectal cancer incidence, age, gender, site, stage, and presentation (emergency vs. elective) are analyzed.

RESULTS

A total of 1,014 specimens obtained from 993 patients were analyzed, showing a progressive population-based increase in colorectal cancer in Barbados during this 20-year time period. There was an increase in right-sided tumors (P < 0.0001) without a concomitant decline in left-sided tumors. There was a significant increase in Dukes A cancers (P < 0.0001) without gender predilection. During the time period, there was a significant reduction in right-sided tumors presenting as emergencies (P < 0.005) without an effect of stage or gender.

CONCLUSIONS

There has been a steady increase in both right-sided and left-sided colonic cancers without gender predilection. The increase in early-stage tumors and reduction in emergency presentations during the latter part of the study suggests value in instituting a formal national colonoscopic screening program to assess its prospective effect on these parameters.

Early life events and later risk of colorectal cancer: age-period-cohort modelling in the Nordic countries and Estonia

BACKGROUND

A lowering of colorectal cancer risk for the birth cohorts born around World War II (WWII) has previously been observed in Norway, a country which suffered some 20% caloric restriction during the war. The purpose of the study was to conduct a similar kind of analysis in the other Nordic countries and Estonia, which were also subjected to various degrees of energy restriction during WWII.

METHODS

All new cases of colorectal cancer in the Nordic countries and Estonia diagnosed between 40 and 84 years of age and born between 1874 and 1953, were collected from the national cancer registries. The incidence data were fitted to an age-period-cohort model.

RESULTS

A transient drop in the estimated colorectal cancer incidence rate was observed for the birth cohorts born around WWII in Estonia, together with a tendency of decreased risk in Sweden and Denmark.

CONCLUSION

The previously observed lowering of colorectal cancer risk for persons born during WWII in Norway also prevails in Estonia. Energy restriction is a possible explanation for these findings, since the countries suffered from varying nutritional conditions during the war. Exogenous factors acting during periods early in life may have an impact on later colorectal cancer risk.

Is there a true "shift" to the right colon in the incidence of colorectal cancer?

OBJECTIVE

Previous studies have reported a migration in the occurrence of colorectal cancer (CRC) toward a proximal colonic location. To assess the potential impact of this, we evaluated recent temporal trends in the United States.

METHODS

Using the nine population-based cancer registries that constitute the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute, we identified primary CRCs diagnosed between 1978 and 1998. Temporal changes were evaluated for 3-yr time periods. Age-adjusted incidence rates and the proportions of new diagnoses of CRC were calculated by site and by race.

RESULTS

We identified 243,861 individuals with CRC during 1978-1998, 51.1% of whom were men. In whites and in blacks, the proportions of new diagnoses of right CRC rose significantly, from 34% and 37% to 40% and 44%, respectively. In contrast, the proportions of left CRC (in whites and blacks) and of rectosigmoid CRC (in whites) decreased significantly over time. For whites and blacks, the age-adjusted incidence rates for right CRC remained unchanged (in whites) or showed a small increase (in blacks), whereas the age-adjusted incidence rates for left CRC (in whites and blacks) and for rectosigmoid CRC (in whites) declined. During 1996-1998, right CRC was the most common site in the oldest age groups (70-79, 80 yr, and older) in whites and in blacks.

CONCLUSIONS

The proximal migration of CRC over time is not attributed to a true increase in the incidence of right CRC. It is explained by a decrease in the incidence of distal CRC coupled with the aging of the population. Older individuals, in whom the burden of CRC is greatest, and in whom right CRC is the most common site, would be the most adversely affected from CRC screening methods that do not assess the total colon.

Effect of age, period of diagnosis and birth cohort on large bowel cancer incidence in a well-defined French population, 1976-1995

The objective of this study was to present trends in colorectal cancer incidence by sex and subsite in a well-defined French population. All of the 4486 large bowel cancer cases registered between 1976 and 1995 in the Burgundy registry of digestive tract cancers was included in this study. Time trends in colorectal cancer incidence were analysed over the 1976-95 period. The effects of age, period and cohort were evaluated using a log-linear Poisson model. The incidence rates for right colon cancer increased over time: + 21.6% (95% CI: + 13.5; + 29.7) per 5-year period in males and +10.4% (95% CI: + 3.4; + 17.3) in females. Left colon cancer rates increased in males (+ 10.6% 95% CI: + 4.6; + 16.6). Left colon cancer in females and rectal cancer incidence rates did not significantly change. Between the 1901 cohort to the 1941 cohort, estimated cumulative risks for right colon cancer increased sharply. The increase was less marked for left colon and the cumulative risk for rectal cancer remained almost stable. Temporal trends were different by subsites and sexes. In conclusion, our results confirm the existence of different trends in colorectal cancer incidence between subsites and sexes. These differences probably reflect aetiological distinctions.

Epidemiology and screening of colorectal cancer

Knowledge of the descriptive epidemiology of colorectal cancer is essential to a better understanding of the aetiology of the disease and the development of screening strategies. Considerable research efforts have been launched over the last 15 years to evaluate the ability of screening tests to decrease the incidence and mortality of colorectal cancer. This chapter provides a worldwide update of the incidence of colorectal cancer and reviews the evidence for screening for colorectal cancer based on published studies.

Time trend and age-period-cohort effects on gastric cancer incidence in Zaragoza and Navarre, Spain

STUDY OBJECTIVE

To describe time trends in gastric cancer incidence in Zaragoza and Navarre, and to investigate time period and birth cohort as determinants of such trends.

DESIGN

Cases from two registries were grouped into five year intervals and the following were calculated: age specific and sex specific incidence rates, and the male to female ratio. Log linear models including age, period of diagnosis, and birth cohort were fitted.

SETTING

The Zaragoza Cancer Registry covers the province of Zaragoza, which has a population of 824,776 (403,755 men and 421,021 women). The Navarre Cancer Registry covers the province of Navarre which has 512,512 inhabitants (254,786 men and 257,726 women). In both cases population figures were based on the late census.

PATIENTS

These comprised incident cases of gastric cancer reported to the Zaragoza Cancer Registry in 1963-87 and to the Navarre Cancer Registry in 1973-87.

MAIN RESULTS

Navarre registered higher adjusted and cumulative rates than Zaragoza for both sexes. In both provinces, there were relative declines in the rates for men and women of 3% and 4% respectively per year. In Zaragoza, the risk of developing stomach cancer fell in generations born between 1888 and 1933, and rose in subsequent birth cohorts in both sexes, while in Navarre the cohort effect showed an approximately linear risk for both sexes. Both provinces recorded increases in risk associated with cohorts born between 1933 and 1943.

CONCLUSION

The incidence rates of gastric cancer fell in both Zaragoza and Navarre. The reason for the greater incidence of gastric cancer in Navarre remains unknown. Trends in rates seem to be mainly linked to birth cohort. Increases in risk in generations born after 1933 may be ascribable to nutritional deficiencies in the early years of life.

Survival for colon and rectal cancer in a population-based cancer registry

Dukes' stage is the most powerful indicator of patient outcome for colorectal cancer. Several cancer survival studies have considered other prognostic variables, but results are often conflicting. We sought to assess the independent value of several clinical and morphological variables in defining colorectal cancer specific survival. 397 colorectal cancer patients diagnosed from 1984 to 1986, and registered in a large bowel cancer registry instituted in a local health district of Northern Italy, were actively followed-up until 31 December 1991. Univariate and multivariate survival analyses were carried out in colon and rectal cancer cases, separately, using the actuarial life-table method and Cox proportional hazard regressions. Crude and specific 5-year survival rates were 37.5 and 41.4%. In univariate analysis, TNM (tumour, nodes and metastases) stage was the strongest predictor of prognosis in both sites. Other variables significantly related to survival were age of patient at diagnosis and pattern of tumour growth in colon cancer, type of differentiation and pattern of tumour growth in rectal cancer. In multivariate analyses, after adjusting for stage, age had a weak but significant negative effect on colon cancer survival, whereas rectal tumours with the infiltrating type of growth had a significantly worse prognosis than those with the expanding type. Colorectal cancer survival should be analysed in the main large bowel subsites in order to define high-risk groups within each TNM stage category.