Changing site distribution of colorectal cancer

Disease characteristics and treatment patterns of Chinese patients with metastatic colorectal cancer: a retrospective study using medical records from China

Background

Colorectal cancer (CRC) is the third most prevalent cancer in China but few large-scale studies were conducted to understand CRC patients. The current study is aimed to gain a real-world perspectives of CRC patients in China.

Methods

Using electronic medical records of sampled patients between 2011 and 2016 from 12 hospitals in China, a retrospective cohort study was conducted to describe demographics and disease prognosis of CRC patients, and examine treatment sequences among metastatic CRC (mCRC) patients. Descriptive, comparative and survival analyses were conducted.

Results

Among mCRC patients (3878/8136, 48%), the fluorouracil, leucovorin, and oxaliplatin (FOLFOX) and other oxaliplatin-based regimens were the most widely-used first-line treatment (42%). Fluorouracil, leucovorin, irinotecan (FOLFIRI) and other irinotecan-based regimens dominated the second-line (40%). There was no a dominated regimen for the third-line. The proportion of patients receiving chemotherapy with targeted biologics increased from less than 20% for the first- and second- lines to 34% for the third-line (p < 0.001). The most common sequence from first- to second-line was from FOLFOX and other oxaliplatin-based regimens to FOLFIRI and other irinotecan-based regimens (286/1200, 24%).

Conclusions

Our findings reflected a lack of consensus on the choice of third-line therapy and limited available options in China. It is evident o continue promoting early CRC diagnosis and to increase the accessibility of treatment options for mCRC patients. As the only nationwide large-scale study among CRC and mCRC patients before more biologics became available in China, our results can also be used as the baseline to assess treatment pattern changes before and after more third-line treatment were approved and covered into the National Health Insurance Plan in China between 2017 and 2018.

Distributions of colorectal cancer in two Chinese cities with contrasting colorectal cancer epidemiology

BACKGROUND AND AIM

The incidence of colorectal cancer (CRC) is rising rapidly in Chinese. We studied the anatomic distributions and characteristics of CRC in Hong Kong (HK) and Chongqing (CQ) with different CRC epidemiology.

METHODS

It was a retrospective study conducted in three large regional hospitals of the two cities. We identified all patients newly diagnosed with CRC between 2003 and 2012. The distribution and characteristics of CRC of the two cities were compared.

RESULTS

Of CRC, 3664 new cases were diagnosed within the study period. CRC was more common in men (>56%) in both cities. The mean age at diagnosis was significantly younger in CQ, the lower prevalence area, than in HK (62.1 vs 70.4 years; P < 0.001). Rectal cancer was the predominant (61.3%) cancer in CQ, but only 18% of cancers in HK were rectal cancer (P = 0.0001). Right-sided colonic cancer, however, was more common in HK than CQ (27.2% vs 17.4%; P < 0.001). Women had more right-sided colonic cancer than men in both cities (P < 0.002), and there was an age-related increase in right-sided colonic cancer in HK but not in CQ. Multivariate analysis showed that older age, female, and living in HK were independent risk factors associated with right-sided colonic cancer.

CONCLUSIONS

There are significant differences in the distribution of CRC between HK and CQ. The discrepancy may be partly accounted by older population and an increase in proximal colonic cancer, particularly in women, in HK.

Subsite-specific dietary risk factors for colorectal cancer: a review of cohort studies

Objective. A shift in the total incidence from left- to right-sided colon cancer has been reported and raises the question as to whether lifestyle risk factors are responsible for the changing subsite distribution of colon cancer. The present study provides a review of the subsite-specific risk estimates for the dietary components presently regarded as convincing or probable risk factors for colorectal cancer: red meat, processed meat, fiber, garlic, milk, calcium, and alcohol. Methods. Studies were identified by searching PubMed through October 8, 2012 and by reviewing reference lists. Thirty-two prospective cohort studies are included, and the estimates are compared by sex for each risk factor. Results. For alcohol, there seems to be a stronger association with rectal cancer than with colon cancer, and for meat a somewhat stronger association with distal colon and rectal cancer, relative to proximal colon cancer. For fiber, milk, and calcium, there were only minor differences in relative risk across subsites. No statement could be given regarding garlic. Overall, many of the subsite-specific risk estimates were nonsignificant, irrespective of exposure. Conclusion. For some dietary components the associations with risk of cancer of the rectum and distal colon appear stronger than for proximal colon, but not for all.

Examining the association between socioeconomic status and invasive colorectal cancer incidence and mortality in California

BACKGROUND

Colorectal cancer (CRC) incidence and mortality rates vary across race/ethnicity. Socioeconomic status (SES) also influences CRC rates; however, these associations might be inconsistent across racial/ethnic groups and tumor subsite. We examined associations between area-level SES and CRC incidence and mortality in a population-based registry study of non-Hispanic Whites, African Americans, Hispanics, and Asians/Pacific Islanders from California.

METHODS

Data on 52,608 incident CRC cases (1998-2002) and 14,515 CRC deaths (1999-2001) aged ≥50 years were obtained from the California Cancer Registry. Based on 2000 U.S. Census data, each cancer case and death was assigned a multidimensional census tract-level SES index. SES-specific quintiles of CRC incidence and mortality rates, incidence rate ratios (IRR) and mortality rate ratios, and 95% confidence intervals (CI) were estimated. Analyses were stratified by anatomical site, including left- versus right-sided tumors, race/ethnicity, and stage of disease.

RESULTS

Overall CRC incidence and SES did not show a clear association, yet patterns of associations varied across tumor subsite and race/ethnicity. Positive associations between SES and CRC incidence were found in Hispanics [SES Q5 v. Q1: IRR = 1.54, CI = 1.39-1.69], irrespective of the subsite. For Whites [SES Q5 v. Q1: IRR = 0.80, CI = 0.77-0.83], and African Americans [SES Q5 v. Q1: IRR = 0.83, CI = 0.70-0.97] inverse associations were observed, predominantly for left-sided tumors. Mortality rates declined with increasing SES in Whites, whereas in Hispanics mortality rates significantly increased with SES.

CONCLUSIONS

Our findings show that SES differences in CRC incidence and mortality vary considerably across anatomical subsite and race/ethnicity.

IMPACT

Studies combining area- and individual-level SES information are warranted.

Anatomical distribution of colorectal carcinoma in Iran: a retrospective 15-yr study to evaluate rightward shift

BACKGROUND

Although more than two third of colorectal cancers are localized on the left side, recent studies suggest a right ward shift in anatomical distribution with increase in proximal colon cancers. The aim of the present study was to determine the anatomical distribution of colorectal cancer in a referral center over a 15 year period.

METHOD

Records of patients who underwent colectomy in the Cancer Institute of Iran from 1994 to 2009 were retrieved. Data including anatomical localization, year of diagnosis, patient age and gender, tumor histology and differentiation, and disease stage were extracted. Tumors located from the cecum to the distal transverse colon were classified as right side and those occurring from the splenic flexure to the descending colon as left-sided. Cancer of rectum and recto-sigmoid junction were considered as rectal cancers.

RESULTS

A total of 442 patients including 220 (49/8%) men and 222 (50/2%) women with mean age 53 were included. Most patients were in stages II and III (47.1% and 33% respectively). There were 157 (35.5 %) colon cancers and 285 (64.5%) rectal cancers. 43.3% of the colon cancers were right sided and 56.7% were left sided. There was no statistically significant increase in right sided cancer during the period of the study. There were no significant differences in age at diagnosis, gender, grade and stage of tumor between the right and the left sided cancers.

CONCLUSION

No proximal shift over time was identified in our study.

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.

CRC surgery trends in Kenya, 1993-2005

BACKGROUND

CRC (CRC) rates are low but increasing in Africa. Data on detection, treatment, and outcome are scarce.

OBJECTIVE

The aim of this study was to evaluate the presentation, treatment, and outcome pattern of CRC and to compare the care processes for two time periods.

SETTING

The setting was Kenyatta National Hospital (KNH), a teaching and referral center.

PATIENTS AND METHODS

A total of 259 patients seen over two time periods (1993-1998 and 1999-2005) were analyzed for admission date, sex, subsite involvement, diagnostic process, treatment, follow-up, and outcome. The distribution of variables between the time periods were analyzed using Student's t-test and chi2 as appropriate. Survival trends were generated using Kaplan Meier method; p<0.05 was statistically significant.

RESULTS

The average number of CRC diagnoses showed a 2.7-fold increase during the study periods. The mean age at presentation was 49.7 years. The mean duration of symptoms was 29.6 weeks; and the commonest subsite was the rectum (55.3%). The overall resection rate was 67.7%. For rectal tumors the abdominoperineal rate was 51.4%. Mortality was higher for poorly differentiated cancer, advanced disease, age>50 years, and emergency surgery. There was no change in the age, duration of symptoms, proportion of patients<40 years, or the colon/rectal ratios of the cancer site. The second time period saw more adjuncts for diagnosis, less in-hospital mortality, and better staging data.

CONCLUSION

CRC peaks during the fifth decade of life in Kenyans. The disease is characterized by late presentation, rectal preponderance, and inadequate pathology data. Improved patient follow-up will unravel the true pattern of disease outcome.

Is there a role for sigmoidoscopy in symptomatic patients? Analysis of a study correlating distal and proximal colonic neoplasias detected by colonoscopy in a symptomatic population

BACKGROUND

Colonoscopy is the gold standard exam to investigate patients with colonic complaints. However, its availability is limited in developing countries. Sigmoidoscopy has been advocated as a first procedure in colorectal cancer screening strategies, in order to select those who need colonoscopy.

AIM

To study the correlation between distal and proximal colonic neoplasias in symptomatic patients 50 years or older and patients 40 to 49 years old who underwent colonoscopy at a gastrointestinal endoscopy unit in 1999 and 2000 with the purpose to evaluate its role in a symptomatic population.

METHODS

All colonoscopies performed in our Department in 1999-2000 were reviewed. The distal colon was defined as the colonic segment aboral to the splenic flexure. Advanced neoplasias were defined as adenomas larger than 10 millimeters and adenocarcinomas.

RESULTS

Of the 2,701 colonoscopies retrieved, 1,125 were enrolled in this study. Prevalence rates for adenoma, advanced adenoma and carcinoma were 28.9%, 4.6% and 4% in the group of 830 patients 50 years or older (mean age 65 years, 491 women). The finding of one small (<10 mm) adenoma in the distal bowel doubled the likelihood of finding a proximal neoplasia (OR = 2.12, 95% CI, 1.27-3.54), and multiple (OR = 3.99, 95% CI, 1.72-9.28) or advanced (OR = 3.73, 95% CI, 1.81-7.7) adenomas increased this risk even further. Of the patients without adenoma or carcinoma in the distal colon, 1.93% had proximal advanced neoplasia. In the group of 40 to 49-year-old patients (n = 395; mean age 44.8 years, 208 women) the prevalence of adenomas (14.9%), advanced adenomas (3.4%), and carcinomas (1.7%) was lower.

CONCLUSIONS

The likelihood of finding a proximal lesion is greater in patients with distal neoplasias. This likelihood is further increased when adenomas are multiple or larger than 10 mm. One out of 52 patients 50 years or older with an apparently normal distal colon has advanced proximal neoplasia. Sigmoidoscopy is not an adequate exam for symptomatic patients aged 50 years or older.

Increasing prevalence of advanced colonic polyps in young patients undergoing colonoscopy in a referral academic hospital in Hong Kong

AIM: To investigate the distribution and frequency of advanced polyps over eight years.

METHODS: 6424 colonoscopies were reviewed during the study period 1998 to 2005. The study period was subdivided into period I: 1998 to 2001 and period II: 2002-2005.

RESULTS: 1856 polyps (33% advanced polyps) and 328 CRCs were detected. The mean ages of the patients with advanced polyps and cancer were 69.2 ± 12.0 and 71.6 ± 13.8 years, respectively. Advanced polyps were mainly left sided (59.5%). Advanced polyps were found in patients ≤ 60 years from 17.7% in periodI to 26.3% in period II (P < 0.05), especially in male subjects ≤ 60 years (21.6% vs 31.6%, P < 0.05). Advanced tubulovillous polyps rose from 21.5% in period I to 29.5% in period II (P < 0.05). Whereas cancers in male patients ≤ 60 years were similar in both periods: 23.2% vs 16.5% (P > 0.05).

CONCLUSION: Advanced polyps increased significantly in the younger male group in the most recent period and there seems to be a shift towards a proximal location.

Changing sites of colorectal cancer in the Israeli Jewish ethnic populations and its clinical implications

Countries at risk for colorectal cancer noted an increase in right-sided colorectal cancer. We examined this in the Israeli Jewish populations. Israel Cancer Registry data, 1982-2001, were computed by sex, age, ethnic group and colorectal cancer site: 'rectal cancer' included the recto-sigmoid junction, 'right-sided' colorectal cancer included proximal colon up to and including the splenic flexure. In both sexes, colorectal cancer trends increased significantly owing to colonic cancer (P<0.01) whereas rectal cancer decreased (P<0.01). Left and right colorectal cancer trends decreased in Israel born people (P<0.01), but in Asia-Africa born people increases were seen at both sites in the male (P=0.02 and 0.06, respectively) and female (P=0.03 and 0.01, respectively) population. In those > or =65 years old, right colorectal cancer trends increased in all men (P=0.05) and women (P=0.01). On comparing data from 1982-1986 with that from 1997-2001 right colorectal cancer showed an increase in both sexes (P<0.01): to 32.7% of male colorectal cancer and 57.6% of female colorectal cancer. In the period 1997-2001, the total male population > or =65 years had increased relatively by 7.5% (P<0.01), and women by 22.6% (P<0.01) and the proportion of right colorectal cancer in > or =65 years olds increased relatively by 10.9% in the male population, and 18.2% in the female population, with one-third of this increase occurring in Russian immigrants arriving after 1990. In conclusion, there is a trend for right colorectal cancer in Jews aged > or =65 years. The proportion and amount of colorectal cancer increased most significantly in older women, which was partially explained by their increasing numbers and by colorectal cancer occurring in recent immigrants from Russia, who were at high-risk for colorectal cancer. These results should influence colorectal cancer screening and diagnostic methodologies used.

Colorectal cancer in Asians: a demographic and anatomic survey in Malaysian patients undergoing colonoscopy

BACKGROUND

Colorectal cancer is one of the most common forms of gastrointestinal cancer in the world today. In the Asia-Pacific area, it is the fastest emerging gastrointestinal cancer.

AIM

To determine the basic demographic features of patients with colorectal cancer and the anatomic distribution and characteristics of the tumour in a local Asian population.

METHODS

We conducted a review of consecutive patients who had undergone colonoscopy from 1999 to 2003 at the University of Malaya Medical Center, Kuala Lumpur, Malaysia.

RESULTS

Analysis was carried out on 3404 patients who underwent colonoscopy. A total of 228 patients (7%) were diagnosed with carcinoma. The mean age of diagnosis (+/-s.d.) was 64.4 +/- 13.1 years. The male to female ratio was 1.15. Polyps were noted in 470 patients (14%). Polyps detected concomitantly with a colorectal cancer were noted in 55 patients (2%). Four patients (0.1%) were diagnosed to have familial adenomatous polyposis coli. Of the 228 patients 209 (92%) had tumours at only one site whereas 19 (8%) had synchronous lesions. Tumours were mainly left sided [198 of 248 patients (80%)] with the majority located in the recto-sigmoid region. Detailed records of treatment were available only in 176 patients. A total of 147 of 176 patients (84%) underwent surgery and 50 (28%) also received adjuvant or palliative chemotherapy (28%). Seven of 154 patients (5%) were diagnosed to have stage A cancers, 64 (42%), stage B, 23 (15%), stage C and 60 (39%), stage D. Multivariate analysis using multiple logistic regression analysis showed that age > or =65 years (OR = 1.78; 95% CI: 1.35- 2.36) and Malay (OR = 2.09; 95% CI: 1.30-3.35) and Chinese (OR = 1.77; 95% CI: 1.77-2.69) race were significant independent predictive factors for colorectal cancer.

CONCLUSIONS

The demography of colorectal cancer is different from western patients. Tumours were mainly left sided in our patients. However, no differences in anatomic location were found between races, men and women and younger and older age groups. Colorectal cancer presented in an advanced stage in the majority of patients.

Changing patterns of colorectal cancer in China over a period of 20 years

AIM: To determine whether any changes have occurred on the patterns of colorectal cancer in China.

METHODS: Data from 21 Chinese articles published from 1980 to 1999, were used to analyze the time trend of colorectal cancer according to the patients’ age at diagnosis, sex, the site of the tumor, stage, and the pathology.

RESULTS: From 1980s to 1990s, the mean age of the colorectal cancer patients has increased. The percentage of the female patients rose. The distribution of colorectal carcinoma shows a predominance of rectal cancer. However, the proportion of proximal colon cancer (including transverse and ascending colon) increased significantly accompanied by a decline in the percentage of rectal cancer. Similarity in the percentage of distal colon cancer between two decades was revealed. In the 1990s, statistically more Stage B patients were found than those in 1980s. In addition, databases show a significant decrease in the Stage D cases. The proportion of adenocarcinoma increased, but the mucinous adenocarcinoma decreased during two decades.

CONCLUSION: These findings indicate that the pattern of colorectal cancer in China has been changing. Especially, a proximal shift due to the increasing proportion of ascending and transverse colon cancer has occurred in China.

Screening and surveillance of colorectal cancer

Although colorectal cancer (CRC) is the second leading cause of cancer deaths in the United States, it is preventable. Screening modalities include fecal occult blood testing, flexible sigmoidoscopy, double-contrast barium enema, and colonoscopy. Colonoscopy allows effective detection and removal of precursor adenomatous polyps and is the dominant CRC screening modality. Emerging technologies include CT and MR colonography and fecal DNA tests. Effective and cost-effective surveillance after polypectomy and curative CRC resection requires balancing the protective effect of polypectomy while maximizing intervals between examinations; thus, estimation of the risk of recurrence determines the intensity of surveillance for individual patients.

Rectal aberrant crypt foci identified using high-magnification-chromoscopic colonoscopy: biomarkers for flat and depressed neoplasia

BACKGROUND

Aberrant crypt foci may represent preneoplastic lesions in the human colon. The prevalence of aberrant crypt foci detected using magnification chromoscopic colonoscopy is known to follow a stepwise progression from normal subjects to those with exophytic adenomas and colon cancer. No studies have addressed the prevalence of rectal aberrant crypt foci in patients with flat and depressed colonic lesions that cluster within the right hemi-colon and may undergo de novo neoplastic transformation.

METHODS

All patients underwent total colonoscopy by a single endoscopist using the Olympus CF240Z magnifying colonoscope. Flat and depressed lesions were diagnosed using targeted indigo carmine chromoscopy. Prior to extubation, pan high-magnification-chromoscopy using indigo carmine was applied to the rectum and the distal 10 cm of mucosa examined using forward and retroflexed views. Aberrant crypt foci were defined as two or more crypts with dilated or slit-like openings that were raised above the adjacent mucosa. Using high-magnification chromoscopic colonoscopy we assessed the prevalence and dysplastic features of aberrant crypt foci in three groups: endoscopically "normal" subjects, patients with flat/depressed adenoma, and flat/depressed cancer.

RESULTS

Two thousand five hundred and fifty-nine patients underwent colonoscopy of which 1,000 were eligible for inclusion. The median number of aberrant crypt foci per patient in the endoscopically normal, adenoma, and cancer group was 1 (range: 0-5), 9 (range: 0-22), and 38 (range: 14-64), respectively. The estimated relative risk of dysplastic aberrant crypt foci when comparing the flat adenoma group with the endoscopically "normal" group was 4.68 (95% CI: 2.23-9.91) with the relative risk for flat cancer versus endoscopically normal group being 21.8 (95% CI: 10.9-23.8). Patients with >5 flat adenomas had higher crypt foci densities than those with <5 adenomas (r=0.53; p<0.001).

CONCLUSIONS

The number of aberrant crypt foci in normal patients, patients with flat adenoma, and flat cancer follow a stepwise incremental change as previously observed for exophytic adenomas and cancer. Detection of aberrant crypt foci in the rectum may be a useful biomarker for proximal colonic flat neoplasia and could be used at index flexible sigmoidoscopic screening to stratify risk of proximal colonic neoplasia. Patients with dysplastic aberrant crypt foci of high density should receive total colonoscopy.

The effectiveness of flexible sigmoidoscopy as the primary method for investigating colorectal symptoms in low-risk patients

BACKGROUND

Flexible sigmoidoscopy as the preferred initial investigation for patients with low-risk colorectal symptoms requires formal evaluation.

METHODS

From August 1999 to July 2001, 323 patients (166 men) attended the one-stop colorectal clinic. All the patients were examined using a 60-cm flexible sigmoidoscope. Presenting symptoms and findings were reviewed.

RESULTS

The mean age of the study patients was 38.6 +/- 11.87 years, with the majority (89.1%) younger than 50 years. Rectal bleeding was the most common problem (86.6%), followed by bowel habit change (13.7%). For 65.6% of the patients, a view to the proximal sigmoid was obtained. The main reason for incomplete assessment was poor bowel preparation (67.5%). The most common finding, in 202 patients (64%), was haemorrhoids. Polyps were found in 9.9% of the patients, whereas four patients (1.2%) with cancer were identified. Overall, 269 patients (83.4%) required no further investigation.

CONCLUSION

Flexible sigmoidoscopy is an effective method for assessing low-risk patients.

The changing distribution and survival of colorectal carcinoma: an epidemiological study in an area of northern Italy

OBJECTIVE

This study analyses the inter-relations of anatomical tumour location, gender, age and incidence rates for colorectal cancer from 1978 to 1999 in an area of northern Italy: the Parma district.

METHODS

Data were obtained from the Parma Cancer Registry. Age-adjusted incidence rates were analysed by gender, age and colorectal cancer subsites. In addition, 5 year observed survival rates were determined.

RESULTS

In the Parma area, the incidence of colorectal cancer is rising. We have observed a true increase in the rate of the age standardized incidence of right colon cancer, linked to an increased incidence of left colon cancer, while the incidence of rectal cancer has remained constant. The frequency of right-sided colon cancer was higher in aged patients, and in women. Age-standardized relative survival of patients after diagnosis of colorectal cancer between 1992 and 1996 was found to be significantly higher than age-standardized relative survival after diagnosis between 1978 and 1982.

CONCLUSIONS

In the Parma area there has been an increased incidence of right colon cancer, linked to an increased incidence of left colon cancer, while the incidence of rectal cancer has remained constant. We feel that this shift, whatever the reason for it, has important implications for the choice of screening techniques.

Anatomical distribution of colorectal cancer over a 10 year period in a district general hospital: is there a true "rightward shift"?

INTRODUCTION

Recent studies of patients with colorectal cancer have suggested a shift towards the proximal colon and an increase in the incidence of right sided colon cancer. This study aimed to determine the anatomical distribution of colorectal cancer over a 10 year period in a district general hospital.

METHODS

Records of patients diagnosed with primary colorectal cancer from 1993 to 2002 were reviewed for demographic data, histology subtype, and anatomical location of the tumour. Tumours located at and proximal to the splenic flexure were defined as right sided cancer and tumours arising distal to the splenic flexure were defined as left sided cancer.

RESULTS

A total of 763 patients were included in the study, of whom all had adenocarcinoma and 99% were white. Sixty nine percent of cancers were left sided and 31% were right sided. Although there was a 4% increase in the proportion of right sided cancers, there was no statistically significant increase using logistic regression analysis. Mann-Whitney U test revealed no significant difference in age at diagnosis between the right and left sided cancers. Although a higher proportion of females were diagnosed with right sided cancer compared with left sided cancer, this was not statistically significant.

CONCLUSION

The anatomical distribution of colorectal cancer has been fairly stable at this hospital with no evidence of a shift towards the proximal colon. No differences were identified in the tumour distribution with respect to gender and age at diagnosis. Our findings support the initial application of flexible sigmoidoscopy for investigating patients with suspected colorectal malignancy and follow up colonoscopy for selected patients to exclude right sided pathology.

Colorectal cancer in African Americans

Colorectal cancer in African Americans has an increased incidence and mortality relative to Whites. The mean age of CRC development in African Americans is younger than that of Whites. There is also evidence for a more proximal colonic distribution of cancers and adenomas in African Americans. African Americans are less likely to have undergone diagnostic testing and screening for colorectal cancer. Special efforts are needed to improve colorectal cancer screening participation rates in African Americans. Clinical gastroenterologists should play an active role in educating the public and primary care physicians about special issues surrounding colorectal cancer in African Americans. Community healthcare groups and gastrointestinal specialists should develop culturally sensitive health education programs for African Americans regarding colorectal cancer. The high incidence and younger age at presentation of colorectal cancer in African Americans warrant initiation of colorectal cancer screening at the age 45 yr rather than 50 yr.

From Colonic Polyps to Colon Cancer: Pathophysiology, Clinical Presentation, and Diagnosis

Epidemiologists, basic researchers, clinicians, and public health administrators unite! Develop and implement a simple, safe, and effective preventive and screening test for colon cancer. The public will willingly and enthusiastically accept such a test. Many thousands of lives are at stake every year.

Changing trends in the incidence, stage, survival, and screen-detection of colorectal cancer: a population-based study

BACKGROUND & AIMS

Colorectal cancer (CRC) screening has been advocated increasingly during the past 2 decades, but there is little direct evidence that it has affected cancer incidence or presentation at the population level. This study assessed concurrent trends in CRC incidence, presentation, survival, mortality, and polypectomies in Olmsted County, Minnesota.

METHODS

Longitudinal observational study was conducted of all Olmsted County residents with colorectal adenocarcinoma first diagnosed in 1980-1999.

RESULTS

Altogether, 889 invasive CRCs were diagnosed among Olmsted County residents from 1980 through 1999. Annual age- and sex-adjusted CRC incidence rates decreased significantly during this period (P = .02) with a 23% decline from 60 per 100,000 in 1980-1984 to 46 per 100,000 in 1995-1999. This was primarily accounted for by a 40% reduction in left-sided CRC (P < .001). The incidence of right-sided CRC remained unchanged, but the proportion of right-sided CRC increased from 46% to 58%. Cancer stage shifted downward, and survival improved over time. The overall proportion of screen-detected CRC rose from 8% to 17%. Annual adjusted adenomatous polypectomy rates increased dramatically from 86 to 320 per 100,000 (P < .001).

CONCLUSIONS

The incidence of CRC in Olmsted County has declined in recent years. An impact of screening is suggested by the observed upward trend in screen-detected cases, a favorable stage shift, and a concurrent rise in polypectomy rates. However, the incidence of right-sided cancer remains unaltered and might be less affected by historically used screening interventions. Most CRCs still present symptomatically, and more effective population screening is needed.

The pathophysiology, clinical presentation, and diagnosis of colon cancer and adenomatous polyps

A review of the pathophysiology, clinical presentation, and diagnosis of colon cancer and colonic polyps is important and timely. This field is rapidly changing because of breakthroughs in the molecular basis of carcinogenesis and in the technology for colon cancer detection and treatment. This article reviews colon cancer and colonic polyps, with a focus on recent dramatic advances, to help the pri-mary care physician and internist appropriately refer patients for screening colonoscopy and intelligently evaluate colonoscopic findings to reduce the mortality from this cancer.

Epidemiological changes in colorectal cancer in Shiraz, Iran: 1980-2000

BACKGROUND

The present study was performed to determine trends in colorectal cancer rates over the past two decades (1970-80 vs 1990-2000) with in a main referral centre in Shiraz, Iran.

METHODS

The Cancer Registry data on all colorectal cancer cases from 1970 to 2000 in Shiraz, Iran, were analysed. Demographic characteristics, clinical features, cancer site and type and stage of cancer were compared in the populations of two different decades.

RESULTS

The age-adjusted incidence of colorectal cancer per 100,000 population per year increased in men from a mean annual incidence of 1.61 in the decade 1970-80 to 4.2 in 1990-2000 (P < 0.05), and in women from 2.35 to 2.72 (P < 0.05). In 1970-80, patients over 60 years had 62.5% of all the colorectal cancers, which decreased to 30% in 1990-2000 (P < 0.05). The distribution of right and left sided cancers were almost equal and showed no significant difference between the two decades (P > 0.05).

CONCLUSION

A marked increase in the incidence of colorectal cancer has been shown in Shiraz. Also, the marked increase in the incidence of colorectal cancer in the 40-60-year-old age group shown in the present study necessitates a more detailed work-up in younger age group patients.

Improvement in quality of colorectal cancer pathology reporting with a standardized proforma--a comparative study

BACKGROUND

Histopathological evaluation is a critical component in the management of patients with colorectal cancer (CRC). It is the single most powerful prognostic indicator in CRC and determines if adjuvant chemotherapy is indicated. The aim of this study was to assess if the introduction of a comprehensive standardized pathology proforma improved the quality of histopathology reporting.

METHODS

A standardized pathology proforma, based on the 1996 minimum dataset for colorectal histopathology reporting, was introduced in our pathology department in 1998. Pathology reports for all colonic resection specimens for 1996 (n = 85) and 2000 (n = 86) were identified, retrieved and entered on to database. Comparison was made with the minimum dataset published in the 1996 guidelines for the management of colorectal cancer.

RESULTS

Demographic details were complete in all cases. Clinical data was incomplete in 57 (67%) patients in 1996 and 63 (73%) in 2000 (ns; chi2). There were 24 (28%) (7 Abdomino-perineal resections (APER)) and 40 (47%) (17 APER's) rectal specimens for 1996 and 2000, respectively. The presence or absence of pathological background abnormalities were commented on in 18 (21%) reports in 1996 and 80 (93%) reports in 2000 (P < 0.01; Fishers exact test (Fisher)). Histological differentiation was commented on in 73 (86%) and 86 (100%) in 1996 and 2000, respectively (P < 0.01; Fisher). Dukes' stage was stated in 33 (39%) reports in 1996 and 86 (100%) in 2000 (P < 0.01; Fisher) but Dukes' stage was calculable in 84 (99%) in 1996 and 86 reports (100%) for 2000 (ns; Fisher). The apical node was commented on in 34 (40%) reports in 1996 and 85 (99%) reports in 2000 (P < 0.01; Fisher). The median (IQR) number of nodes assessed in 1996 was 8 (5-12) compared to 12 (8-17) in 2000 (P < 0.001; Mann-Whitney (MW)). Complete resection was mentioned in 74 (87%) reports in 1996 and 86 (100%) in 2000 (P < 0.01; Fisher). Regarding rectal specimens, the circumferential resection margin (CRM) was commented on in 19 of 24 specimens in 1996 and 38 of 40 specimens in 2000 (ns; Fisher). Relationship to the peritoneal reflection was commented on in 1 (1%) rectal specimen in 1996 and 30 (35%) in 2000 (P < 0.001; Fisher).

CONCLUSION

The introduction of a standardized proforma for reporting CRC resection specimens improves the quality of histopathological reporting. This aids decision-making regarding adjuvant chemotherapy or radiotherapy and further surveillance.

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.

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.

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.

Rationale for colonoscopy screening and estimated effectiveness in clinical practice

Colonoscopy screening has the highest anticipated level of effectiveness of the available colorectal cancer screening techniques. Its long-term cost-effectiveness is also comparable with or superior to other modalities. Evidence for the expected reduction in colorectal cancer incidence and mortality varies with colonoscopy screening from 50% to 90%, for reasons that are not fully understood. Maintaining a high standard of performance is critical with regard to achieving the highest level of effectiveness possible.

The anatomical distribution of colorectal polyps at colonoscopy

BACKGROUND

Colorectal carcinoma is one of the most common causes of cancer-related deaths in Australia. The distribution of polyps in the colon may effect the efficacy of a screening modality. The aim of this study was to determine the age-matched anatomic location and histologic type of colorectal polyps observed at colonoscopy over a 10-year period at our endoscopy unit.

STUDY

Endoscopy reports on 2,578 patients were reviewed; polyp/lesion histology and location (left, right, or both) were determined in 2,553.

RESULTS

Of all polyps observed, 1,310 (51%) cases were left-sided, 510 (20%) were right-sided, and 733 (29%) were synchronous. Adenomas were present in 1,659 cases (65%); of these, 734 (44%) were left-sided only and 405 (24.5%) were right-sided only. Carcinoma was observed in 189 (7%) cases, of which 71 (37.5%) were left-sided only. There was an increased right-sided prevalence of adenoma or carcinoma with age (p = 0.0029).

CONCLUSION

This was not a screening study, but it has shown that a significant number of adenomas and carcinomas lie proximal to the splenic flexure. Thus, in the absence of left-sided lesions, it is expected that examination of the colon limited to the splenic flexure would miss 23% of such lesions. The increasing right-sided prevalence of these lesions with age suggests that evaluation of the proximal bowel is particularly important in older people.

Adenoma characteristics as risk factors for recurrence of advanced adenomas

BACKGROUND AND AIMS

The link between adenoma characteristics at baseline colonoscopy and adenoma recurrence is poorly understood. We assessed whether the number, size, location, or histology of resected adenomas was related to the probability of recurrence of advanced lesions.

METHODS

Analyses were based on 1287 men and women in the wheat bran fiber (WBF) study, a randomized, double-blind trial of WBF as a means of decreasing the probability of adenoma recurrence over a period of 3 years. Multiple logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Recurrence of advanced adenomas (>1 cm or tubulovillous/villous histology) was higher among individuals with adenomas >1 cm compared with those with adenomas <0.5 cm (OR, 2.69; 95% CI, 1.34-5.42) and among those with proximal than those with distal adenomas (OR, 1.65; 95% CI, 1.02-2.67). No association was observed for adenoma number or histology. A shift in location from the distal colon and rectum at baseline (54.6%) to more proximal recurrent adenomas (45.2%), including advanced lesions (42.8%), was observed.

CONCLUSIONS

Large or proximally located adenomas are important indicators of recurrence of advanced lesions. Because most recurrences were detected in the proximal colon, careful surveillance of this area is warranted.

Flexible sigmoidoscopy and the changing distribution of colorectal cancer: implications for screening

BACKGROUND AND AIMS

There has been a significant proximal shift in the distribution of colorectal cancer (CRC) in Northern Ireland over recent decades. The aim of this study was to investigate the potential implications of this proximal shift in CRC distribution on the efficacy of flexible sigmoidoscopy (FS) as a screening tool.

PATIENTS AND METHODS

The site distribution of 5153 CRCs was available from the Northern Ireland Colorectal Cancer Register for the period 1990-1997. Similar data on 1241 CRCs between 1976 and 1978 were available from a previous study. Data on the site reached by FS were obtained from a prospectively collected endoscopy database at one of Northern Ireland's main teaching hospitals for the period 1993-1998.

RESULTS

There was a significant proximal shift in CRC distribution between the two periods (23.5% proximal to the splenic flexure between 1976 and 1978 v 36.7% between 1990 and 1997; p<0.001). The descending colon was visualised during 74.4% of FS examinations. By combining the observed extent of FS examination with CRC site distribution, it was calculated that FS could have visualised 68.8% of CRCs between 1976 and 1978 but only 56.0% between 1990 and 1997. Extrapolating these data to a Northern Ireland screening programme involving FS and faecal occult blood testing suggests that significantly more CRCs could have been detected between 1976 and 1978 than between 1990 and 1997 (51.7% v 48.2%, respectively; p=0.03).

CONCLUSIONS

This study confirms the previously documented left to right shift in CRC distribution in Northern Ireland and demonstrates that if this shift continues, FS will become less successful as a screening tool than is currently predicted.

Incidence trends for colorectal cancer in California: implications for current screening practices

PURPOSE

The sensitivities of different screening methods for precancerous adenomas may affect the anatomical distribution of colorectal cancers. We used statewide data from California to describe time trends in the distribution of colorectal carcinoma.

SUBJECTS AND METHODS

Between 1988 and 1996, 110,378 cases of colorectal cancer were recorded in the California Cancer Registry database. Tumors proximal to, but not including, the sigmoid colon were termed "right-sided." The remaining tumors, excluding the anus, were termed "left-sided." Multivariable analyses were used to determine the effects of age, sex, and race on changes in tumor location over time.

RESULTS

During the study period, the annual incidence of colorectal cancer decreased steadily, from 200 to 162 cases per 100,000 residents. The decrease in left-sided tumors was about twice that observed on the right (-24.3% vs -11.6%). This disparity remained significant when adjusted for age, sex, and race (P = 0.0001).

CONCLUSION

The incidence of colorectal cancer in California is decreasing, particularly for left-sided (distal) tumors. Current screening recommendations, which emphasize examination of the distal colon, may need to be expanded to include the entire colon.

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.

Colorectal carcinoma among ethnic Chinese in Singapore: trends in incidence rate by anatomic subsite from 1968 to 1992

BACKGROUND

Recent epidemiologic studies have suggested that the anatomic distribution of colorectal carcinoma may have undergone a distal to proximal shift over several decades, which has been attributed variously to environmental and genetic factors as well as preventive intervention.

METHODS

Trends in subsite distribution and the incidence rate of colorectal carcinoma among Chinese in Singapore between 1968 and 1992 were explored using data from the Singapore Cancer Registry (n = 10,489). Age-standardized incidence rates were computed and compared further using age-period-cohort models by subsite and gender.

RESULTS

The proportion of lesions in the distal colon was found to have increased from 23.2% to 24.4% whereas that for the proximal colon and rectum were fairly consistent over the past 25 years. Our results also showed that age-standardized rates have doubled in proximal lesions (2-3% annually) and more than doubled in distal lesions (3-4% annually) whereas rates in rectal carcinoma have shown a slight increase or stability over time. The patterns of change in all subsite tumors could be attributed to a significant birth cohort effect.

CONCLUSIONS

The results of the current study suggest that incidence rates have increased rapidly with no distal to proximal shift observed among ethnic Chinese in Singapore over the past 25 years. The pattern of change differs from findings reported in high incidence countries such as the U. S. and parts of Europe, suggesting that the preventive intervention and early diagnostic capabilities that may have played an important role in these countries have had less effect in Asia. The rapid overall increase in the incidence rate of colon carcinoma supports the role of dietary and other environmental factors as possible risk factors.

Influence of hospital and clinician workload on survival from colorectal cancer: cohort study

OBJECTIVE

To determine whether clinician or hospital caseload affects mortality from colorectal cancer.

DESIGN

Cohort study of cases ascertained between 1990 and 1994 by a region-wide colorectal cancer register.

OUTCOME MEASURES

Mortality within a median follow up period of 54 months after diagnosis.

RESULTS

Of the 3217 new patients registered over the period, 1512 (48%) died before 31 December 1996. Strong predictors of survival both in a logistic regression (fixed follow up) and in a Cox's proportional hazards model (variable follow up) were Duke's stage, the degree of tumour differentiation, whether the liver was deemed clear of cancer by the surgeon at operation, and the type of intervention (elective or emergency and curative or palliative intent). In a multilevel model, surgeon's caseload had no significant effect on mortality at 2 years. Hospital workload, however, had a significant impact on survival. The odds ratio for death within 2 years for cases managed in a hospital with a caseload of between 33 and 46 cases per year, 47 and 54 cases per year, and >/=55 cases per year (compared to one with </=23 cases per year) were respectively 1.48 (95% confidence interval 1.03 to 2.13), 1.52 (1.08 to 2.13), and 1.18 (0.83 to 1.68).

CONCLUSIONS

There was no detectable caseload effect for surgeons managing colorectal cancer, but survival of patients treated in hospitals with caseloads above 33 cases per year was slightly worse than for those treated in hospitals with fewer caseloads. Imprecise measurement of clinician specific "events rates" and the lack of routinely collected case mix data present major challenges for clinical audit and governance in the years ahead.

No difference in stem cell somatic mutation between the background mucosa of right- and left-sided sporadic colorectal carcinomas

Epidemiological, morphological, and molecular differences exist between carcinomas of the right and left sides of the large bowel. To investigate whether this is reflected in differences in somatic mutation frequency in the background mucosa, mutation of the neutral O-acetyltransferase gene (oat) was quantified in histologically normal resection margins from 20 informative (heterozygous) patients with caecal or ascending colon cancer (11 males, median age 75 years) and 20 with sigmoid colon or rectal cancer (10 males, median age 70 years). Mutant discordant crypts lacking O-acetyltransferase activity were visualized by mPAS staining and classified as wholly or partially involved by the mutant phenotype; median frequencies (x10(-4) were compared (Mann-Whitney U-test) after assessing a sample of more than 10,000 crypts per case. No significant difference was found between the frequencies of wholly involved mPAS-positive crypts in background mucosa of left- and right-sided cancers (p = 0.4569), indicating that tumours on both sides of the colon are associated with similar levels of lifetime-accumulated stem cell mutational load. However, partially involved mPAS-positive crypts were significantly more frequent in mucosa from left-sided cancers (p < 0.04), indicating increased mutational activity during the previous 12 months. Analysis of mucosa proximal and distal to left-sided cancers showed that this increase was due to a statistically higher frequency of partially involved crypts in proximal mucosa, which probably resulted from the obstructive effects of the tumour causing increased exposure of the proximal mucosa to luminal carcinogens and/or epithelial regeneration in response to low-grade inflammation or ischaemia. The findings indicate that although left-sided colonic cancer is commoner than right-sided cancer in the British population, carcinomas on both sides of the large bowel arise in a background of similar levels of stem cell mutational activity.

Continued change in the distribution of colorectal carcinoma

BACKGROUND

The aim of this study was to determine whether the previously reported shift in carcinoma from the left colon to the right colon has progressed.

METHODS

The charts of 2169 patients admitted to one institution between 1979 and 1994 with a diagnosis of colorectal carcinoma were reviewed retrospectively. The study was divided into four equal intervals. The large bowel was divided into five regions: right, transverse, left, sigmoid and rectum.

RESULTS

Right-sided lesions increased from 20.6 to 29.9 per cent (P = 0.001) and rectal lesions decreased from 22.0 to 11.3 per cent (P = 0.0002) from the first to the fourth study interval. The frequency of transverse, left and sigmoid colon lesions remained relatively constant.

CONCLUSION

The continuing trend of increased incidence of right-sided lesions and decreased incidence of rectal lesions was documented. Any screening examination for carcinoma requires total examination of the 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.

A marked increase in the incidence of colorectal cancer over two decades in southwest Finland

The Finnish Cancer Registry's data on all colorectal cancer cases from 1971 to 1990 in southwest Finland, an area of mean population of 433,000, were analyzed. The age-adjusted incidence of colon cancer per 100,000 population increased in men from 8.5 in 1971-1980 to 13.5 in 1981-1990 and in women from 10.3 to 13.1. The incidence of male rectal cancer increased from 9.8 to 11.1 and in women from 6.4 to 7.1. The proportion of elderly patients clearly rose and, in 1981-1990, patients over 65 years of age had 68.4% of all colon cancers and 73.9% of all rectal cancers. There was a proximal shift in the site distribution of cancers: the proportion of rectal cancers decreased from 45.9% in 1971-1980 to 40.9% in 1981-1990. This change was most marked in men. There was no change in the spread and operability of colorectal cancers during the two decades. There was an increase in colon cancer mortality while the mortality of rectal cancer cancer slightly decreased.

Socioeconomic circumstances and the risk of bowel cancer in Northern Ireland

OBJECTIVE

To describe the variation in the incidence of colorectal cancer across Northern Ireland and relate it to factors associated with community deprivation.

DESIGN

This was a cross sectional descriptive study.

SETTING

Incidence data were obtained from a population based register for the period 1990-91. Small areas were characterised by their "affluence", or lack of it, by deriving a Townsend deprivation score for each electoral ward, using information from the 1991 census. PARTICIPANTS, MAIN OUTCOME MEASURES, AND STATISTICAL METHODS: The age standardised incidence was calculated for all colorectal cancer cases diagnosed histologically in 1990-91. Electoral wards were grouped into quintiles of the population after ranking of their Townsend scores and the association with incidence was studied using Poisson regression.

RESULTS

The age standardised colorectal cancer incidence ranged from 22.5 (for quintile 1) to 29.9/100,000 (quintile 5) for men but the trend for women was less regular and rates were 18.4, 23.8, 27.3, 26.5, and 23.9/100,000 for quintiles 1-5 respectively (that is, from the most "affluent" to the most "deprived" fifths of the population). After adjusting for age and sex in Poisson regression, there was a significant association between the total colorectal cancer incidence and levels of community deprivation. The rate ratio for the most deprived quintile of the population (compared with the least) was 1.28 (95% CI 1.06,1.53). The effect was stronger for rectal cancer than for colonic cancer. There was no association between community deprivation and the cancer stage at diagnosis.

CONCLUSIONS

In this population, the colorectal cancer incidence is associated with the level of material deprivation. The disease stages at the time of diagnosis in patients from more deprived areas seem to be comparable with those of patients from affluent areas. As others have shown, associations such as these are not explicable entirely on the basis of the distribution of known risk factors. Further research is needed to determine plausible mechanisms for the association.

Colorectal cell kinetics

The assessment of cell proliferation in colorectal tissue may provide information with both prognostic and therapeutic implications. A variety of methods are available, including flow cytometric estimations of S phase fraction, immunohistochemical and autoradiographic visualization of exogenous and endogenous proliferation proteins, and morphological and stathmokinetic techniques. There is some correlation between Dukes stage and proliferation state features, and there is increased proliferative activity throughout the adenoma-carcinoma sequence. Data on cell proliferation rates are difficult to obtain. When correctly applied, the metaphase arrest technique remains the 'gold standard' of measuring proliferation, but its usefulness in clinical practice is limited. Recent studies have employed dual measurement flow cytometry and double labelling techniques to produce rate data.

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.