Epidemiological evidence for distinguishing subsites of colorectal cancer

Colorectal Cancer in Korea: Characteristics and Trends

Aims and Background

Colorectal cancer is the fourth leading cause of malignancy in Korea. However, there have been few reports concerning the clinical or pathological characteristics of patients in this area. The aim of this study was to examine the characteristics and trends of colorectal cancer in Korea.

Methods

The 1,468 patients with a histologic diagnoses of colorectal cancer between 1990 and 1997 at the Seoul National University Hospital, Seoul, Korea, were retrospectively examined. The data source was the medical record database of the Hospital.

Results

The mean age at diagnosis was younger than in Western countries (57.4 years for colon cancer and 55.6 years for rectal cancer). Rectal cancer was found to be more frequent than colon cancer. However, the proportion of colon cancer has been steadily increasing with time. The changes in the colon-to-rectal ratio mainly arose from an increase in left-sided colon cancer. Moderately differentiated adenocarcinoma was also increasing. Colon cancer patients demonstrated a more advanced stage than the rectal cancer patients. Surgery was performed in 93.7% of the patients as a first course of treatment.

Conclusions

The characteristics of Korean colorectal cancer patients were remarkably different from those seen in Western countries in age and primary tumor site distribution. However, the differences were less evident with time. A nationwide population-based registry is required to confirm the results of the study.

Emergence of Colorectal Cancer in West Africa: Accepting the Inevitable

It seems not too long ago that colon and rectal cancer is a "rare" disease in rural Africa; however, over the last 30 years in West Africa, published evidence has shown decade by decade increases in the incidence of colorectal cancer (CRC). Therefore, CRC should now be accepted as a recognized disease in native Africans; nevertheless, we must acknowledge that the incidence is a fraction of what obtains in the developed countries of Europe and America. This presentation will attempt to examine the emergence of CRC within the West African axis over the last four decades.

Combined assessment using optical colonoscopy and computed tomographic colonography improves the determination of tumor location and invasion depth

INTRODUCTION

An accurate assessment of the depth of tumor invasion in patients with colon cancer is an important part of the preoperative evaluation. Whether computed tomographic colonography (CTC) or optical colonoscopy (OC) is better to accurately determine tumor location and invasion depth has not been definitively determined. The aim of this study was to determine the diagnostic accuracy of tumor localization and tumor invasion depth of colon cancer by preoperative OC alone or combined with CTC.

METHODS

Study participants include 143 patients who underwent both preoperative CTC using automated CO₂ insufflation and OC from July 2012 to August 2013.

RESULTS

The accuracy of tumor localization was significantly better with CTC than with OC (OC, 90%; CTC, 98%; P < 0.05). No tumor in the descending colon was localized accurately via OC alone. The accuracy of tumor invasion depth was better with CTC plus OC than with OC alone (OC, 55%; CTC, 73%; P < 0.05).

CONCLUSIONS

OC combined with CTC provides a more accurate preoperative determination of tumor localization and invasion depth than OC alone.

Sporadic carcinoma of the colon-rectum in young patients: a distinct disease? A critical review

INTRODUCTION

Colon carcinoma is rare in patients under 40 years but incidence is increasing. Results regarding outcome of this age group have been controversial and difficult to interpret. Some authors have reported a worse prognosis related to advanced stage at diagnosis and cancer-aggressive behavior. We tried to assess whether sporadic colon carcinoma in young patients is a distinct disease with different etiology and how this reflects on outcome.

METHODS

Most relevant papers published and indexed on PubMed in the last 20 years were reviewed. Epidemiological data were retrieved from the Surveillance, Epidemiology and End Results database and discussed.

DISCUSSION

Stage-specific analyses adjusted for age have demonstrated that prognosis is related to tumor stage regardless of age. Advanced stage is partly due to tumor biology and to delayed diagnosis. Younger patients show a better performance status that allows aggressive multimodal treatment.

CONCLUSION

Colon carcinoma in young adults appears to be a distinct disease characterized by biological aggressiveness, but prognosis is not worse due to a better performance status at time of surgical intervention.

Trends in colorectal cancer incidence: a period and birth-cohort analysis in a well-defined French population

BACKGROUND

France stands among high-risk areas for colorectal cancer. Different trends in CRC incidence are reported around the world. The aim of this study was to provide temporal trends in CRC incidence over a 30-year period in a French well-defined population.

METHODS

Between 1976 and 2005, 17,028 new cases were registered by the Burgundy digestive cancer registry. The mean variations in age-standardized incidence rates were estimated using a Poisson regression adjusted for age for each gender and location. The cumulative risk by birth cohort of developing a cancer over the age range 0-74 years was estimated using an age-cohort model.

RESULTS

Incidence rates for right and left colon cancers increased more rapidly in males (respectively +11.7% and +10.3% on average by 5-year period) than in females (respectively +5.9% and +6.1%). It remained stable for sigmoid cancers in males (-0.1%) and decreased in females (-5.2%). It also decreased for rectal cancers both in males (-2.7%) and in females (-2.0%). The cumulative risk increased from 3.9% for males born around 1900 to 4.9% for those born around 1930 and then slightly decreased (4.5% among those born around 1950). It remained at the same level for females born around 1900 (2.7%) as for those born around 1930 (2.7%) and then slightly increased (2.9%) for those born around 1950. For right colon cancers, the cumulative risk increased strikingly in successive birth cohorts from 0.53% to 1.2% in males and 0.55% to 0.77% in females. The corresponding cumulative risks for the left colon were 0.24% and 0.42% in males and 0.14% and 0.29% in females. For sigmoid cancer, they decreased from 1.59% to 1.08% in males, and 0.88% to 0.80% in females.

CONCLUSION

Temporal variations in incidence rates of colorectal cancers differed according to subsite, suggesting different aetiological factors and implications for diagnosis and screening strategies. Total colonoscopy must be the preferred strategy in high-risk groups or after a positive faecal occult blood test.

Does socioeconomic status influence the prospect of cure from colon cancer--a population-based study in Sweden 1965-2000

AIM OF STUDY

Differences in the survival of colon cancer patients by socioeconomic status have been demonstrated in several populations, but the underlying reasons for the differences are not well understood. By simultaneously estimating the proportion of patients cured from colon cancer and the survival times of the 'uncured' we hope to increase understanding of how socioeconomic status affects survival following a diagnosis of colon cancer.

METHODS

We conducted a population-based cohort study of 58,873 patients diagnosed with colon cancer in Sweden 1965-2000. Socioeconomic status was classified based on occupation. We fitted mixture cure models and Poisson regression models adjusted for age, sex and calendar period.

RESULTS

We observed higher excess mortality, lower proportion cured and shorter survival times among the uncured in patients from lower socioeconomic groups compared to the highest socioeconomic group. There was no evidence that the gap between the socioeconomic groups reduced over time. Farmers had the lowest odds of cure (odds ratio (OR) 0.85, 95% confidence interval (CI) 0.75-0.95) compared to higher non-manual workers followed by self-employed (0.91, 0.81-1.03), manual workers (0.93, 0.85-1.03) and lower non-manual workers (0.98, 0.89-1.08).

CONCLUSION

Patients from lower socioeconomic groups in Sweden experience worse survival following a diagnosis of colon cancer. Differences exist in both the cure proportion and the survival time of the uncured, suggesting that socioeconomic differences cannot be attributed solely to lead time bias.Although this study has furthered our understanding of socioeconomic differences in survival, more detailed studies are required in order to identify, and subsequently remove, the underlying reasons for the differences.

Colorectal adenoma characteristics as predictors of recurrence

PURPOSE

The identification of groups with a high risk of colorectal adenoma recurrence remains a controversial issue for clinicians. This study was designed to assess the predictive value of initial patient and adenoma characteristics of the three-year recurrence.

METHODS

The study population was composed of 552 patients with resected colorectal adenomas who completed the European Fiber-Calcium Intervention trial. At both baseline and three-year examinations, the characteristics of adenomas were recorded according to a standardized protocol. The main outcomes measured were the three-year overall recurrence, recurrence of multiple adenomas, recurrence of advanced adenomas (size > or = 1 cm or tubulovillous/villous architecture or moderate/severe dysplasia), and proximal and distal recurrence.

RESULTS

A three-year recurrence was observed in 122 patients (22.1 percent), and more than one-half of them had recurrent adenomas on the proximal colon. After adjustment for patient characteristics and treatment allocation, the number of adenomas and their proximal location at baseline were the main predictors of recurrence. In comparison with patients who had one or two adenomas on the distal colon, patients with three or more adenomas with at least one of them located on the proximal colon had a much higher risk of overall recurrence (5.3; 95 percent confidence interval, 2.7-10.3), proximal recurrence (8.5; 95 percent confidence interval, 4.1-18), and advanced adenoma recurrence (5.5; 95 percent confidence interval, 2.4-12.6).

CONCLUSIONS

Follow-up colonoscopies in patients with adenomas should include careful examination of the proximal colon. The time interval between follow-up examinations could probably be extended beyond three years in patients who have only one or two distal adenomas.

Socioeconomic variation in colon cancer tumour factors associated with poorer prognosis

Analysis of population-based registry data (n=7393) showed that more deprived colon cancer patients had lower risk of the mucin-producing adenocarcinoma subtype, proximal subsite (to the descending colon), and no greater risk of high-grade tumours. Tumour factors therefore appear unlikely to account for socioeconomic gradients in survival.

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.

Trends in colorectal cancer incidence in Norway by gender and anatomic site: an age-period-cohort analysis

The purpose of this study was to examine the secular trend of colorectal cancer in Norway by gender and subsite. All new cases of cancer in proximal colon, distal colon and rectum diagnosed between 1958 and 1997 in Norway were included in the study, altogether 34 202 and 34 097 cases for men and women, respectively. The incidence data were fitted separately for each gender and subsite to an age-period-cohort model. An increase in incidence of colorectal cancer was seen from 1958 to 1997 for both men and women, although a moderate attenuation of the increase has taken place in the last 15-20 years. This observation is most pronounced for cancer of the distal colon, but is also evident for proximal colonic and rectal cancers. For the distal colon and rectum, the period effect is more important than the cohort effect for both genders, whilst opposite for the proximal colon. The main estimated trend for cohort effects is a steady increase for both men and women, apart from an unexpected drop in incidence among the cohorts born during or shortly after World War II. These findings indicate that different aetiological risk factors may act on cancers of the proximal and distal part of the large bowel and further suggest that exogenous risk factors acting very early in life may play a more important role for colorectal cancer than previously recognized.

Changing site distribution of colorectal cancer in Japan

PURPOSE

In North America and other high-risk areas, there has been a proximal shift in the subsite distribution of colorectal cancer. We wanted to determine whether any similar change has occurred in Japan, and where the incidence of this disease has increased sharply.

METHODS

Data from the Reports of the Japanese Society for Cancer of the Colon and Rectum were used to analyze the time trend of colorectal cancer in Japan between 1974 and 1994 according to the patients' age at diagnosis and sex, and the site of the tumor within the colon or rectum.

RESULTS

The percentage of patients over the age of 70, especially females, increased. The increase in the percentage of right-sided colon cancer in colorectal cancer cases was accompanied by a continuous decline in the percentage of rectal cancer in both sexes at all ages. In general, the percentage of right-sided colon cancer in colon cancer cases was stable in men, but increased in women. The rate among patients older than 70 years increased in men, but predominated and remained stable in women. No proximal shift in colon cancer was found in either sex under the age of 69.

CONCLUSION

These findings indicated that a proximal shift in the subsite distribution of colorectal cancer has occurred in Japan. This rightward shift of colorectal cancer is due to the decreasing proportion of rectal cancer. Furthermore, the increasing proportion of older patients, especially females, may be another major determinant of the changing colon cancer subsite distribution.

Diet and cancer: assessing the risk

Globally, colorectal cancer (CRC) is a leading cause of mortality from malignant disease. Case-control and cohort studies provide strong support for a role of diet in the aetiology of CRC. However to establish causal relationships and to identify more precisely the dietary components involved, intervention studies in human subjects are required. Cancer is an impractical endpoint in terms of numbers, cost, study duration and ethical considerations. Consequently, intermediate biomarkers of the disease are required. This review aims to provide an overview of the intermediate endpoints available for the study of CRC, particularly non-invasive faecal biomarkers. Examples of their use in dietary intervention studies are given.

Proximal shift of colorectal cancer in the Australian Capital Territory over 20 years

BACKGROUND

Several studies in other countries have demonstrated a change in subsite distribution of colorectal cancer, with increasing proximal cancers. Confirmation of such a change in Australia would have implications for screening and diagnosis of colorectal cancer.

AIMS

To determine whether there has been an increase in the proportion of proximal colorectal cancers in Australia, and whether there have been changes in other clinical and pathological aspects of colorectal cancer.

METHODS

A study of the hospital files of patients with colorectal cancer diagnosed and treated at all hospitals in the Australian Capital Territory (ACT) between 1989 and 1995 was compared with data from a published study of patients diagnosed between 1969 and 1976.

RESULTS

There was a proximal shift of cancers with a significant increase in the proportion of tumours in the hepatic flexure, ascending colon and caecum, more marked for females than males. There was a corresponding reduction in distal colorectal cancers. Time from onset of symptoms to diagnosis decreased, risk factors for colorectal cancer were noted more frequently, and endoscopy replaced barium enema X-ray as the main diagnostic modality. The resectability of cancers increased, stay in hospital and 30 day mortality declined. Despite apparent earlier presentation and improved surgical resectability, the proportion of patients with localised disease (Dukes' stage A and B) had not changed significantly.

CONCLUSIONS

We have detected a number of changes in clinical and pathological aspects of colorectal cancer over a 20 year period in the ACT, including a proximal shift in the subsite distribution of colorectal cancer. These changes suggest that proximal and distal colorectal cancers may have a different aetio-pathogenesis, and have implications for the investigation of patients with suspected colorectal cancer and in screening high-risk groups.

Tea and coffee consumption and risk of colon and rectal cancer in middle-aged Finnish men

The association between coffee and black tea consumption and the subsequent risk of colon and rectal cancer was investigated within a Finnish clinical trial cohort. One hundred eleven cases of colon cancer and 83 cases of rectal cancer were diagnosed over a median of 9.0 years of follow-up. Proportional hazards regression models were used to derive adjusted relative risk (RR) and 95% confidence intervals (CI) for the association between coffee and tea consumption and cancer incidence. After controlling for confounders, coffee was not significantly associated with colon or rectal cancer. A positive association was seen for increased consumption of tea drinking and colon cancer. Compared with persons who did not drink tea, those who consumed <1 cup/day had an RR of 1.40 (95% CI = 0.84 - 2.33) and those who consumed > or = 1 cup/day had an RR of 2.09 (95% CI = 1.34-3.26, p for trend = 0.001). In contrast, tea consumption had little effect on rectal cancer incidence. This study does not support the hypothesis that coffee and tea protect against colorectal cancer risk. However, given the strength of the tea-colon cancer association and the significant gradient of risk we observed across level of intake, further epidemiologic research of this relationship in other populations seems warranted.

Family history of cancer and risk of colorectal cancer in Italy

Subjects with a family history of colorectal cancer (CRC) are at increased risk of CRC, but quantification of the risk in different populations, the possible differences in risk according to localization of the cancer and the association of family history of other cancers with CRC risk are still open issues. We have therefore analysed data from a multicentric case-control study conducted in six Italian areas between 1992 and 1996 of 1225 incident cases of colon cancer, 728 cases of rectal cancer and 4154 controls admitted for acute conditions to the same network of hospitals as the cases. Unconditional logistic regression models including terms for gender, age, study centre, years of education and number of siblings were used to estimate the odds ratios (ORs) of CRC according to various aspects of history of CRC and other cancers in first-degree relatives. The OR for family history of CRC was 3.2 (95% confidence interval, CI, 2.5-4.1) for colon cancer and 2.2 (95% CI 1.6-3.1) for rectal cancer. Colon cancer was significantly associated with a family history of stomach (OR 1.4), bone (OR 2.1) and kidney (OR 2.3) cancers, while rectal cancer was significantly associated with a family history of lymphomas (OR 2.8). There was a 30% higher risk of colon and rectal cancer in subjects with a family history of any cancer, excluding intestine. The ORs for family history of CRC were 5.2 for colon and 6.3 for rectum when the proband's age was below 45 years. The ORs were similar when the affected relative was a parent or a sibling and in different strata of age of relative(s). For subjects with two or more first-degree relatives with CRC, the risk was 6.9 for the right colon, 5.8 for the transverse and descending colon, 3.8 for the sigma, 3.2 for the rectosigmoid junction and 1.9 for the rectum. This study confirms that a family history of CRC in first-degree relatives increases the risk of both colon and rectal cancer, the association being stronger at younger ages and for right colon.

Overview of the epidemiology of colorectal cancer

INTRODUCTION

The epidemiology of colorectal cancer has generated more interest recently, because recent developments in genetics, molecular biology, and genetic epidemiology have increased our understanding of the role of genes in the etiology of colorectal cancer. Interactions between genetic susceptibility and environmental factors in the etiology of cancer may be easier to define.

EPIDEMIOLOGY

Colorectal cancer is common in the Western world and is rare in developing countries. A sharp increase is seen in Eastern Europe and Japan.

ETIOLOGY

Molecular genetics has shown that accumulation of genetic changes is important in the development of colorectal cancer. Mutations in at least four to five genes are required for the formation of a malignant tumor. Environmental mutagenic factors may determine which susceptible individuals grow carcinomas. Environmental risk factors for colorectal cancer are found in a western diet, rich in fat, meat, and animal protein and low in fiber, fruit, and vegetables. The complex interrelations between food components make it difficult to define the precise role of specific food factors.

PREVENTION

Conclusive evidence of the effectiveness of primary prevention of colorectal cancer via dietary measures or nonsteroidal anti-inflammatory drugs is lacking. Secondary prevention by interrupting the adenoma carcinoma sequence is an actual possibility, its effectiveness, however, needs to be determined. Molecular genetics holds a promise for identifying populations at high risk for colorectal cancer, therefore, targeting the screening to make it more cost-effective.

Colon cancer in the elderly: evidence for major improvements in health care and survival

Time trends in therapeutic approaches and in the prognosis of colon cancer for patients aged 75 years and above have been investigated in comparison with corresponding trends for younger patients using a population-based series of 2089 colon cancer patients diagnosed between 1976 and 1990 in the Côte-d'Or area (478,000 inhabitants), Burgundy, France. Significant progress has been achieved in the management of patients with colon cancer in both age groups, but trends have been more noticeable in patients aged 75 years and above. In the elderly, the proportion of cancers limited to the digestive tract wall showed a 3-year average increase of 2.8% (P = 0.02) and the frequency of curative surgery an average increase of 8.6% (P < 0.001), so that it was performed in 80% of cases in the last 3-year period. Operative mortality decreased by 2.5% between 3-year periods (P < 0.004). Crude 5-year survival rates in elderly patients increased from 15% in the 1976-78 period to 29% in the 1985-87 period (P < 0.001), the corresponding figures being 36% and 44% (P > 0.10) in younger patients.

Molecular study of sex steroid receptor gene expression in human colon and in colorectal carcinomas

BACKGROUND

Sex steroid hormones influence function of the human gastrointestinal tract. Although the specific receptor proteins have been identified in surgical specimens of both intestinal mucosa and colorectal carcinomas, it is still unknown whether they are expressed in intestinal epithelial cells.

METHODS

Expression of androgen receptor (AR) protein and estrogen receptor (ER) protein was studied by Scatchard analysis and ELISA (for ER only) in surgical specimens of normal-appearing mucosa, colorectal carcinomas, isolated colonocytes, and human colorectal carcinoma cell lines. Northern analysis was applied to identify the appropriate mRNAs, followed by the sensitive technique of reverse transcription-polymerase-chain-reaction (RT-PCR).

RESULTS

AR protein was identified in all surgical specimens analyzed and ER protein in 10 out of 13 normal-appearing mucosa specimens and 4 out of 7 colorectal carcinomas. The receptor proteins were not found in isolated colonocytes or in the transformed cell lines. RT-PCR confirmed that none of the isolated normal colonocytes or transformed colorectal carcinoma-derived cells expressed these mRNAs. Intestinal smooth muscle cells and fibroblasts were found to express sex steroid receptor mRNAs.

CONCLUSIONS

Both receptors are present in human large intestine but are expressed in stromal cells and not in intestinal epithelial cells. We hypothesize that sex steroids may influence the function of colonocytes indirectly through stromal-epithelial interactions.

Registration of colorectal cancer in Scotland: an assessment of data accuracy based on review of medical records

Colorectal cancer accounts for a substantial burden of morbidity and mortality in the population. While the need for reliable incidence data may be self-evident, the quality of cancer registration data has rarely been assessed. In Scotland during 1993, the medical records of a random sample of cancer registrations attributed to the year 1990 were sought. The sample contained 238 registrations of colorectal cancer, 217 (91%) of which had relevant medical records available for review. Registration details were reabstracted from available records and compared with data in the registry. Discrepancies in identifying items of data (surname, forename, sex and date of birth) were recorded in eight cases (3.7%, 95% confidence intervals 1.2-6.2%). None would have disturbed record linkage. Discrepancy rates of 3.7% (1.2-6.3%) in postcode of residence at the time of diagnosis (excluding differences arising through boundary changes), 8.3% (4.6-12.0%) in 'anniversary date' (excluding differences of 30 days or less), 2.8% (0.6-5.0%) in histological verification status and 13.5% (8.9-18.1%) in morphology code (excluding 'inferred' morphology codes) were recorded. Twelve cases (5.5%, 2.5-8.6%) were deemed not to warrant site codes for cancer of the colon (ICD-9 153) or rectum (ICD-9 154). In many respects, therefore, the data held about registrations of colorectal cancer in Scotland appear to show a high level of accuracy. Completeness of case ascertainment has still to be formally assessed.

Differences in cancer incidence and mortality among socio-economic groups

OBJECTIVES

In this article studies on the association between socioeconomic status (SES) and risk for cancer at different sites are reviewed.

METHODS

The review is restricted to studies conducted in affluent societies, after 1970. Only studies using income, education and/or occupation as SES indicators are included.

RESULTS

A more or less consistent positive association between SES and cancer risk was found for colon and breast cancer. More or less consistent inverse associations were found for lung, stomach, oropharyngeal and esophageal cancer. Inconsistent associations were reported for cancer of the rectum and pancreas. Possible explanations for SES differences in cancer risk are discussed with special emphasis on lifestyle variables related to cancer risk.

CONCLUSIONS

It is concluded that it is still unclear whether the reported associations can be (partially) attributed to lifestyle related risk factors for cancer such as smoking, nutritional habits, drinking habits and reproductive factors.

Socioeconomic status and colon cancer incidence: a prospective cohort study

The association between socioeconomic status and colon cancer was investigated in a prospective cohort study that started in 1986 in The Netherlands among 120,852 men and women aged 55-69 years. At baseline, data on socioeconomic status, alcohol consumption and other dietary and non-dietary covariates were collected by means of a self-administered questionnaire. For data analysis a case-cohort approach was used, in which the person-years at risk were estimated using a randomly selected subcohort (1688 men and 1812 women). After 3.3 years of follow-up, 312 incident colon cancer cases were detected: 157 men and 155 women. After adjustment for age, we found a positive association between colon cancer risk and highest level of education (trend P = 0.13) and social standing (trend P = 0.008) for men. Also, male, upper white-collar workers had a higher colon cancer risk than blue-collar workers (RR = 1.42, 95% CI 0.95-2.11). Only the significant association between social standing and colon cancer risk persisted after additional adjustment for other risk factors for colon cancer (trend P = 0.005), but the higher risk was only found in the highest social standing category (RR highest/lowest social standing = 2.60, 95% CI 1.31-5.14). In women, there were no clear associations between the socioeconomic status indicators and colon cancer.

Anatomic site distribution of colon cancer by race and other colon cancer risk factors

PURPOSE

Black patients with colon cancer are more likely to have poorer survival from colon cancer than are white patients. To determine whether anatomic site differences might contribute to survival differences, we compared anatomic site distributions of black and white patients.

METHODS

As part of the Black/White Cancer Survival Study, we collected medical record data for 1,045 patients from Atlanta, New Orleans, and San Francisco/Oakland, newly diagnosed in 1985 or 1986 and interviewed 745 of them.

RESULTS

In polychotomous logistic regression analysis, site was related to stage, grade, and histologic type and among women with age, parity, and possibly smoking. However, it was not related to race, except perhaps among men age 65 and older, among whom blacks were somewhat likely to have more transverse and distal, not proximal, cancer. These relations were consistent across subgroups and were independent of other factors examined.

CONCLUSION

Results suggest that site differences are unlikely to contribute to poorer survival commonly observed among black colon cancer patients in the United States.

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

In a previous investigation, statistical modelling was used to examine the relationship between large-bowel-cancer incidence and age, time period and birth cohort by anatomic sub-site and sex, using data from the Connecticut Tumor Registry (CTR) for the period 1950 to 1984. This analysis revealed differences in age-period-cohort patterns that suggested etiologic distinctions among sub-site groupings and between the sexes. To test the generalizability of the Connecticut findings, we have conducted a similar age-period-cohort analysis using data from the Danish Cancer Registry (DCR) for the period 1953 to 1987. Cancers of the large bowel were classified into 6 anatomic sub-sites: cecum, ascending colon, transverse colon, descending colon, sigmoid colon and rectum. Data were fitted to log-linear age-period-cohort models. If we interpret differences in age-period-cohort patterns as reflecting etiologic distinctions, the Denmark analysis, in conjunction with the Connecticut findings, was consistent with there being etiologic distinctions between cancers of the colon vs. the rectum in both males and females, between cancers of the cecum and the ascending colon vs. the remainder of the colon in females and between males vs. females for cancers of the sigmoid colon and rectum. Cancers of the cecum and the ascending colon were the most similar between males and females. Due to the ambiguities of age-period-cohort modelling, these should be considered only tentative conclusions that can be tested by analytical epidemiologic studies.

Trends in subsite distribution of colorectal cancers and polyps from the Vaud Cancer Registry

BACKGROUND

Changes in the subsite distribution of malignant and benign colorectal tumors over the last few years have been reported in several series. They may be related to changes in diagnostic accuracy or to real changes in incidence.

METHODS

Trends in incidence and subsite distribution of colorectal cancers and polyps between 1978 and 1988 have been analyzed using data from the Cancer Registry of the Canton Vaud, Switzerland (530,000 inhabitants in 1981), which has adopted standardized methods for identification and registration not only of malignant, but also of benign colorectal lesions.

RESULTS

Age-standardized incidence rates for malignant tumors of the ascending colon in men increased from 4.6/100,000 in 1978-80 to 6.4/100,000 in 1987-88, and in women from 4.9 to 6.5. Incidence was approximately stable for transverse, descending, and sigmoid colon, whereas a decline was observed for "other and unspecified" colon cancers. Rates for rectal cancer declined by over 10% in both sexes, although the trends were not linear across calendar periods in each sex. Overall colorectal cancer incidence was relatively stable in both sexes in the Vaud population. In terms of proportional distribution, the percentage of cases in the ascending colon increased from 27% in 1978-83 to 33% 1984-88 (P < 0.05). Reliable incidence data for polyps were available for 1979 and from 1982 to 1988. Rates for ascending colon polyps increased from 1.0/100,000 in 1979-83 to 5.0/100,000 in 1987-88 in men, and from 0.4 to 2.7 in women. Incidence rates were higher, although to a lesser extent, for transverse colon and for descending colon polyps in men only. As in the case of malignant tumors, incidence rates declined between the early and the late 1980s for rectal polyps as well as for "other and unspecified" colon polyps. Overall, colorectal polyp incidence was stable around 45/100,000 for men but increased from 19 to 27/100,000 for women. With reference to proportional distributions, significant increases were observed for ascending (from 8.4% to 16.8%) and, to a lower degree, transverse colon (from 8.4% to 11.0%). No appreciable change was observed for any other subsite, except a decline for "other and unspecified" colonic polyps.

CONCLUSIONS

The observation of similar changes in distribution for benign and malignant tumors may suggest the importance of improved diagnostic accuracy (particularly total colonoscopy) for lesions arising in the proximal colon.

Variation in colorectal cancer incidence in the United States by subsite of origin

BACKGROUND

Colorectal cancer incidence rates vary widely internationally, by race and gender, and have changed over time. Investigation of the patterns by subsite within the colorectum may suggest clues of possible etiologic significance for further study.

METHODS

Using population-based data on more than 120,000 cases diagnosed 1976-1987 in the United States Surveillance, Epidemiology, and End Results program, colorectal cancer incidence was evaluated by subsite of origin.

RESULTS

Little racial variation was evident for cecum and ascending colon cancers; rates were higher among blacks than whites for transverse and descending colon cancers but lower for sigmoid, rectosigmoid, and rectal cancers. Rates generally increased over time for most colon sites, especially sigmoid colon among white men, but declined slightly for rectal cancer among whites. The sex ratio increased among whites monotonically from 1.12 for cecum to 1.71 for rectal cancers. The distal colon cancer excess among men was most notable at older ages, contrasting with slightly higher rates among women at younger ages. Geographic differences were particularly notable for transverse and rectosigmoid colon cancers.

CONCLUSIONS

It may be fruitful for future studies to evaluate factors affecting colorectal carcinogenesis by subsite of origin.

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

In order to investigate etiologic distinctions among the anatomic sub-sites of the large bowel by sex, the relationship between large-bowel-cancer incidence and age at diagnosis, time period at diagnosis, and birth cohort was analyzed by anatomic sub-site and by sex, using data from the Connecticut Tumor Registry. Included in the study were all incident large-bowel-cancer cases occurring between 1950 and 1984 among Connecticut residents aged 40 to 79. Cancers of the large bowel were classified into 5 anatomic sub-sites: ascending colon (including cecum), transverse colon (including flexures), descending colon, sigmoid colon, and rectum (including rectosigmoid junction, anal canal, and anus). The data were fitted to log-linear age-period-cohort models. For each of the sub-sites, the age-period-cohort patterns for males and females differed. Within each sex, sub-site groupings with common patterns were indicated. Among males, the age-period-cohort patterns for the colon sub-sites were fairly similar; but the pattern for the rectum differed markedly from that for the colon sub-sites. There were secondary differences among the colon sub-sites that pointed to a secondary distinction between the right and the left colons. Among females, the age-period-cohort patterns for the left colon sub-sites and the rectum were fairly similar. The pattern for the transverse colon differed moderately from that of the left colon, and differed substantially from that of the rectum and the ascending colon. The ascending colon differed markedly from each of the other sub-sites. It is possible that these differences in age-period-cohort patterns reflect etiologic distinctions among sub-site groupings and between the sexes.

Sex differences in colonic function: a randomised trial

There are sex differences in large bowel cancer rates and a variety of other gastrointestinal disorders possibly because of differences in gut biology. To determine whether men and women have different gastrointestinal responses when consuming identical intakes of dietary fibre, 16 women and 18 men consumed liquid formula diets and 'quick breads' with 0 g, and 10 g, and 30 g of fibre as wheat bran and vegetable fibre. The five test diets were consumed in random order, each treatment lasting 23 days. Mean transit time was faster (p = 0.02), and stool weights (g/day) were greater (p = 0.0005) for men than women. Neutral detergent fibre (NDF) excretion was greater in men (p = 0.01), and women tended to digest more NDF (p = 0.06). Men and women seemed to respond differently to wheat bran and vegetable fibre with regard to NDF excretion and digestibility. There were no gender differences in the faecal pH or moisture content. Concentrations and daily excretion of the secondary bile acids, lithocholic and deoxycholic acid, were greater for men than women (p < 0.05). Gender differences in bowel function and bile acid excretion, observed when men and women consumed the same amounts of dietary fibre, may be relevant for understanding colonic disease aetiology and for undertaking future dietary intervention trials.

Adenoma--carcinoma sequence or "de novo" carcinogenesis? A study of adenomatous remnants in a population-based series of large bowel cancers

Although it is well known that colorectal cancers can arise on a preexisting adenoma or de novo, the relative importance of these two pathways is still highly controversial. The authors studied the proportion of cancers with adenomatous remnants in a nonselected population-based series of 1630 resected colorectal cancers, so that they could estimate by subsite the importance of the adenoma-carcinoma sequence. Four factors appeared to be related independently to the presence of adenomatous tissue within cancers in a multiple logistic model: tumor extension, growth pattern, location, and size. It appeared that infiltrating and ulcero-infiltrating tumors, which represented 39.8% of all resected colorectal cancers, very rarely displayed adenomatous tissue (0.5%), whereas it was more common in fungating and ulcero-fungating cancers (25.8%; P less than 0.001). In these exophytic cancers, the presence of adenomatous tissue was related very closely to the tumor size and extension, and it was seen in as many as 83% of small cancers (less than 2 cm) limited to the mucosa or submucosa. Right colon cancer showed consistently fewer adenomatous remnants than left colon or rectal cancer. These figures suggest that there are roughly two types of colorectal cancers, one of the infiltrating or ulcero-infiltrating type, which usually would arise de novo and account for approximately 40% of all colorectal cancer cases, and the exophytic type, which would mainly follow an adenoma-carcinoma sequence, although some might be de novo cancers, in particular in the right colon.

Epidemiology, management, and prognosis of malignant large bowel polyps within a defined population

The population based registry of digestive tract tumours established for the department of Côte d'Or, France (population 480,000) was used to study the epidemiology and management of malignant large bowel polyps. In a 10 year period (1976-85), 146 cases were recorded in the area. Age standardised incidence rates were 2.7 per 100,000 for men and 1.4 per 100,000 for women. Although incidence rates increased significantly during the study period, large bowel cancer diagnosed as a malignant polyp remained relatively rare (6.2% of all registered large bowel cancers). Two malignant polyps (1.4%) were less than 1 cm in diameter, 34 (23.3%) were more than 30 mm. Sixty patients were treated by endoscopic polypectomy, four by contact radiotherapy, 21 by surgical local excision, 58 by colectomy (10 preceded by polypectomy), and three by colotomy. Operative mortality was 8.2% after intra-abdominal surgery, 4.8% after local surgical excision, and 0% after polypectomy (p less than 0.05). All deaths occurred in patients over 65 years. The five year cumulative recurrence rates were 8.9% after surgical excision and 11.3% after endoscopic polypectomy (NS). The corresponding five year net survival rates were 86.1% and 95.9%. Endoscopic excision alone can be considered a sufficient treatment for adenomas with malignant change unless there is evidence of incomplete resection or a high risk of lymph node metastases.

Morphologic analysis of digestive cancers from the registry of Vaud, Switzerland

Detailed data and statistics per each morphological site of various digestive neoplasms were obtained for the period 1976-87 from the Vaud Cancer Registry datafile, a population-based cancer registration scheme covering about 530,000 inhabitants from the French-speaking part of Switzerland. Tabulations presented include absolute number of cases (1,041 oral and pharyngeal, 545 oesophageal, 1,131 gastric, 83 small intestine, 1,980 colon, 1,267 rectal, 357 liver, 328 gallbladder and 725 pancreatic cancers), percent distributions, age-standardised rates, sex ratios and 5-year survival. The report has essentially a descriptive value, and should be viewed as a contribution towards quantification, in a well surveilled population of the West-central part of Europe, of the proportional distribution of digestive neoplasms by morphological type, and corresponding incidence and survival rates. Among the points deserving specific attention, there are the elevated frequency of upper digestive tract cancers, the very high male-to-female ratios for squamous cell carcinomas, adenocarcinomas of the oesophagus and hepatocellular carcinomas of the liver, the female excesses in infiltrating carcinoids of the colon, transitional and squamous cell carcinomas of the rectum and adenocarcinomas of the gallbladder, and the crossover in male-to-female ratio in squamous cell carcinoma along the digestive tract (i.e. from 6.0 at the level of the mouth/pharynx to 0.5 in the rectum). As concerns survival, rates were higher for lymphomas and sarcomas than for carcinomas in oral cavity and stomach, similar for carcinoids and carcinomas in the small bowel (about 35% at 5 years), as well as for colon (34%) and rectal (37%) cancers. Some of the findings, such as the higher survival of carcinomas arising from polyps in the colon and rectum, or the higher proportion of cholangiocellular and combined cholangio- and hepatocellular carcinomas in females than in males find plausible prognostic or aetiologic correlates, but others, such as the large proportions of squamous and transitional cell cancers of the rectum in females are more difficult to explain. These and several other indications emerging from careful examination of the data herein presented underline the interest of morphological analyses of digestive tract cancers.