Age and sex distribution of patients with colorectal cancer

Distinguishing Rectal Cancer from Colon Cancer Based on the Support Vector Machine Method and RNA-sequencing Data

Colorectal cancer (CRC) is the third most commonly diagnosed cancer worldwide. Several studies have indicated that rectal cancer is significantly different from colon cancer in terms of treatment, prognosis, and metastasis. Recently, the differential mRNA expression of colon cancer and rectal cancer has received a great deal of attention. The current study aimed to identify significant differences between colon cancer and rectal cancer based on RNA sequencing (RNA-seq) data via support vector machines (SVM). Here, 393 CRC samples from the The Cancer Genome Atlas (TCGA) database were investigated, including 298 patients with colon cancer and 95 with rectal cancer. Following the random forest (RF) analysis of the mRNA expression data, 96 genes such as HOXB13, PRAC, and BCLAF1 were identified and utilized to build the SVM classification model with the Leave-One-Out Cross-validation (LOOCV) algorithm. In the training (n=196) and the validation cohorts (n=197), the accuracy (82.1 % and 82.2 %, respectively) and the AUC (0.87 and 0.91, respectively) indicated that the established optimal SVM classification model distinguished colon cancer from rectal cancer reasonably. However, additional experiments are required to validate the predicted gene expression levels and functions.

Colorectal Cancer in Young Adults

The study was carried out to promote a greater awareness of the potential for colorectal cancer in young adults under 40 years of age. During the 8 years between 1986 and 1993, 237 patients with adenocarcinoma of the colon and rectum were operated at the Uludağ University Hospital. Of these 237 cases, 46 patients under 40 years old were reviewed retrospectively. They accounted for 19.4% of the total number of patients with carcinoma of the colon and rectum operated during the same period. Rectal bleeding was the most common presenting symptom. The mean duration of time from the onset of symptoms to diagnosis was 5.8 months. The rectosigmoid area was the most frequently involved site (80%). Seventy-six percent of the patients had Dukes’ stage C or D tumors. Forty-eight percent of the tumors were either poorly differentiated or mucinous. The cumulative survival rate at 5 years was 43.4%. Patients under 40 years old with carcinoma of the colon and rectum are usually symptomatic and have advanced disease at the time of presentation. Although colorectal cancer is usually a disease of older patients it is becoming more common in younger populations.

The relationship between right-sided tumour location, tumour microenvironment, systemic inflammation, adjuvant therapy and survival in patients undergoing surgery for colon and rectal cancer

Background:

There has been an increasing interest in the role of tumour location in the treatment and prognosis of patients with colorectal cancer (CRC), specifically in the adjuvant setting. Together with genomic data, this has led to the proposal that right-sided and left-sided tumours should be considered as distinct biological and clinical entities. The aim of the present study was to examine the relationship between tumour location, tumour microenvironment, systemic inflammatory response (SIR), adjuvant chemotherapy and survival in patients undergoing potentially curative surgery for stage I–III colon and rectal cancer.

Methods:

Clinicopathological characteristics were extracted from a prospective database. MMR and BRAF status was determined using immunohistochemistry. The tumour microenvironment was assessed using routine H&E pathological sections. SIR was assessed using modified Glasgow Prognostic Score (mGPS), neutrophil:lymphocyte ratio (NLR), neutrophil:platelet score (NPS) and lymphocyte:monocyte ratio (LMR).

Results:

Overall, 972 patients were included. The majority were over 65 years (68%), male (55%), TNM stage II/III (82%). In all, 40% of patients had right-sided tumours and 31% had rectal cancers. Right-sided tumour location was associated with older age (P=0.001), deficient MMR (P=0.005), higher T stage (P<0.001), poor tumour differentiation (P<0.001), venous invasion (P=0.021), and high CD3⁺ within cancer cell nests (P=0.048). Right-sided location was consistently associated with a high SIR, mGPS (P<0.001) and NPS (P<0.001). There was no relationship between tumour location, adjuvant chemotherapy (P=0.632) or cancer-specific survival (CSS; P=0.377). In those 275 patients who received adjuvant chemotherapy, right-sided location was not associated with the MMR status (P=0.509) but was associated with higher T stage (P=0.001), venous invasion (P=0.036), CD3⁺ at the invasive margin (P=0.033) and CD3⁺ within cancer nests (P=0.012). There was no relationship between tumour location, SIR or CSS in the adjuvant group.

Conclusions:

Right-sided tumour location was associated with an elevated tumour lymphocytic infiltrate and an elevated SIR. There was no association between tumour location and survival in the non-adjuvant or adjuvant setting in patients undergoing potentially curative surgery for stage I–III colon and rectal cancer.

Rectal and colon cancer: Not just a different anatomic site

Due to differences in anatomy, primary rectal and colon cancer require different staging procedures, different neo-adjuvant treatment and different surgical approaches. For example, neoadjuvant radiotherapy or chemoradiotherapy is administered solely for rectal cancer. Neoadjuvant therapy and total mesorectal excision for rectal cancer might be responsible in part for the differing effect of adjuvant systemic treatment on overall survival, which is more evident in colon cancer than in rectal cancer. Apart from anatomic divergences, rectal and colon cancer also differ in their embryological origin and metastatic patterns. Moreover, they harbor a different composition of drug targets, such as v-raf murine sarcoma viral oncogene homolog B (BRAF), which is preferentially mutated in proximal colon cancers, and the epidermal growth factor receptor (EGFR), which is prevalently amplified or overexpressed in distal colorectal cancers. Despite their differences in metastatic pattern, composition of drug targets and earlier local treatment, metastatic rectal and colon cancer are, however, commonly regarded as one entity and are treated alike. In this review, we focused on rectal cancer and its biological and clinical differences and similarities relative to colon cancer. These aspects are crucial because they influence the current staging and treatment of these cancers, and might influence the design of future trials with targeted drugs.

Genetic mechanisms in interval colon cancers

BACKGROUND AND AIM

The factors underlying the development of interval colon cancers are not well defined and are likely heterogeneous. We sought to determine whether there are distinct molecular properties associated with interval colon cancers.

METHODS

Colon cancers diagnosed within 5 years of a complete and well-prepped colonoscopic examination were identified over a 7-year period at a single institution. The clinical and pathological features of the tumors were defined. Analysis of DNA mismatch repair (MMR) and genotyping of a panel of oncogenes associated with colon cancer were performed.

RESULTS

Forty-two interval colon cancers were diagnosed at an average age of 70 years. 69 % of tumors were located in the right colon. 41 % of tumors exhibited DNA microsatellite instability (MSI). Loss of staining of DNA MMR proteins by immunohistochemistry (IHC) was confirmed in 82 % of the MSI-positive tumors. Among tumors with abnormal MSI and IHC, 54 % exhibited somatic methylation of the MLH1 promoter, but the remaining 43 % exhibited molecular features indicative of underlying Lynch syndrome (LS). The frequency of somatic mutations in the KRAS, BRAF, NRAS, and PIK3CA oncogenes was similar between interval cancer cases and controls.

CONCLUSIONS

Interval colon cancers are not distinguished by the activation of the KRAS, NRAS, BRAF, or PIK3CA oncogenic pathways. However, MSI pathway defects are present in a significant proportion of interval colon cancers. Underlying LS may explain nearly half of these MSI-positive cases, and the remaining cases appear to represent sporadic serrated pathway tumors.

Distribution trends of colorectal adenoma and cancer: a colonoscopy database analysis of 11,025 Chinese patients

BACKGROUND AND AIM

A left-to-right shift of colorectal cancer (CRC) has been reported in Western studies. However, few Asian studies have investigated the anatomic distribution of colorectal adenoma and CRC. We aimed to describe the time trends in the distribution of colorectal adenoma and CRC in a Chinese population.

METHODS

A colonoscopy database was reviewed, and all consecutive patients with lower gastrointestinal symptoms who underwent colonoscopy from 1998 to 2009 were identified. Data, including patients' sex, age, symptoms, and the number and anatomic locations of colorectal adenoma and CRC, were documented.

RESULTS

A total of 11,025 patients were included in the final analysis; 1012 and 363 patients were diagnosed with colorectal adenoma and CRC, respectively. Overall, there were more distal than proximal adenomas (54.4% vs 37.9%), and the proportion of proximal adenomas remained stable from 1998-2006 to 2007-2009 (38.2% vs 37.6%). Similarly, there were more distal than proximal CRC (56.5% vs 42.4%), and the proportion of proximal CRC declined from 45.8% in 1998-2006 to 38.4% in 2007-2009. Colorectal adenoma and CRC were equally distributed among both sexes. For elderly patients (> 50 years), there was a non-significant trend towards more proximal adenoma and CRC.

CONCLUSIONS

The present study suggests no distal-to-proximal shift of colorectal adenoma and CRC among the Chinese population in Shanghai over the past 12 years. The distribution pattern of colorectal adenoma and CRC of Chinese patients is different from that of Western patients, who had more colorectal lesions located in the distal part.

Risk analyses for screening sigmoidoscopy based on a colorectal cancer (CRC) population

OBJECTIVE

Although colonoscopy can be effective in the prevention of colorectal cancer (CRC), it requires many endoscopic facilities, has a high patient burden and risk of complications, and it is expensive. The aim of this study was to determine the risk for proximal CRC and to identify subgroups in which screening sigmoidoscopy can be effective.

MATERIAL AND METHODS

A database search was carried out on all patients who underwent endoscopy of the lower gastrointestinal (GI) tract between 1997 and 2005. All patients diagnosed with CRC were included. Variables including age, gender and the presence of distal colonic neoplasia were used for risk analyses.

RESULTS

In total, 783 patients were diagnosed with CRC. Tumour was located in the proximal colon in 68/255 (27%) of the patients <65 years. Of the patients <65 years, 22% (57/255) had proximal CRC without synchronous distal lesions and would thus have been missed by sigmoidoscopy screening. Among patients >65 years, 41% (216/528) were diagnosed with proximal CRC, significantly more often in women than in men (p <0.001). In 35% of patients (185/528) proximal CRC without distal colonic neoplasia was found, significantly more than in those under 65 years of age (p <0.001).

CONCLUSIONS

Significantly more proximal localized CRC would have been missed by sigmoidoscopy screening in elderly patients, especially in women. In subjects <65 years of age, sigmoidoscopy screening allows detection of almost 80% of CRC cases and might suffice as a screening method.

Colorectal carcinoma: a retrospective, descriptive study of age, gender, subsite, stage, and differentiation in Iran from 1995 to 2001 as observed in Tehran University

PURPOSE

Colorectal carcinoma is one of the most common cancers in the world as well as in Iran. There are differences in subsite of the carcinoma when considering age and gender. This study was designed to describe the distribution of colorectal carcinoma by age at diagnosis, gender, and subsite of the tumor. These factors also are evaluated in conjunction with disease stage and tumor differentiation at the time of diagnosis.

METHODS

Data from 419 patients from a population that receives no screening between April 1995 and March 2001 operated on in the Cancer Institute and Imam Khomieni Hospital with a diagnosis of colorectal cancer were used to describe distribution of the colorectal carcinoma by age, gender, tumor subsite and pathology, and stage at diagnosis.

RESULTS

There were 403 (96.2 percent) cases of adenocarcinoma. Males and females constituted 52.4 and 47.6 percent of cases, respectively. The mean age was 52.3 years. Patients were divided into two age groups (40 years and younger, and older than 40 years); 16.4 percent of patients had tumors in the proximal colon and 83.6 percent in distal parts. Most patients were Stage II and III (48.1 and 33.4 percent, respectively). Tumor subsite distribution was almost the same between the two age groups (aged 40 years and younger: proximal, 18.5 percent, and distal, 81.5 percent; older than aged 40 years: proximal, 15.7 percent, and distal, 84.3 percent). Most patients in the younger age group were Stage III (45 percent) and in the older age group were Stage II (53.2 percent; P<0.001). Tumor differentiation proportions in patients aged 40 years and younger were: good, 24.4 percent; moderate, 53.6 percent; poor, 22 percent; and in patients older than aged 40 years were: good, 41.5 percent; moderate, 52.6 percent; poor, 5.9 percent (P<0.001). There were no differences in stage and tumor differentiation between two genders, but most of the patients with tumors in proximal colon were males (62.5 percent; P=0.1).

CONCLUSIONS

Most of the colorectal carcinomas were in distal parts in our study, so most of these carcinomas can be detected by proctosigmoidoscopy. Because younger patients had more advanced disease, the importance of screening and "clinical suspicion" in the young is important.

Distinct molecular patterns based on proximal and distal sporadic colorectal cancer: arguments for different mechanisms in the tumorigenesis

BACKGROUND AND AIMS

Colorectal cancer (CRC) ranks as the fourth most frequently diagnosed cancer worldwide. CRCs that arise proximally or distally to the splenic flexure show differences in epidemiologic incidence, morphology, and molecular alterations, suggesting the existence of two categories of CRC based on the site of origin. The aim of the present work is to investigate the histological and molecular differences between CRCs located proximally and distally to the splenic flexure, and their potential involvement in tumor prognosis and therapeutic strategies.

METHODS

We evaluated 120 patients affected by sporadic CRC for clinicopathologic features, microsatellite instability (MSI), loss of heterozygosity (LOH) of chromosomes 18q, 8p, and 4p; they were also investigated for hMlh1, hMsh2, Fhit, p27, and Cox-2 immunostaining.

RESULTS

The mucinous histotype was more frequent in the proximal than in the distal CRCs (p<0.004). The frequency of MSI phenotype was higher in proximal than in distal tumors (p<0.001); moreover, reduced or absent hMlh1, Fhit, p27 immunohistochemical expressions were more frequent in proximal than in distal tumors (p<0.001 and 0.01 for p27). In contrast, the frequency of LOH in 18q was higher in distal than in proximal tumors (p=0.002). No significant differences were observed between proximal and distal tumors in the frequency of LOH in 8p and altered expression of hMsh2 and p53 protein.

CONCLUSION

These different features may reflect different genetic pathways of carcinogenesis and support the hypothesis of a different mechanism of cancer development between the proximal and the distal colon, with potential implications in the therapeutic approach.

Age and time as factors in the left-to-right shift of the subsite of colorectal adenocarcinoma: a study of 213,383 cases from the California Cancer Registry

GOALS

Using a data set of more than 200,000 cases, we can measure the effects of age, time, sex, and race/ethnicity on the shift of the site of origin of colorectal adenocarcinoma from the left to the right side.

BACKGROUND

As people become older, there is a shift of the site of origin of adenocarcinoma of the colorectum from the left to the right side. Although some studies do show some relationship of this shift, in addition to age, to race/ethnicity and to sex, there are no large, total population-based data studying the effects of these factors and time trends in this shift.

STUDY

213,383 cases of adenocarcinoma of the colorectum for the years 1988 to 2003 from the California Cancer Registry have been studied.

RESULTS

The left-to-right shift increases significantly with increasing age and year of diagnosis, and is greater in women than in men and is greater in whites than in other racial/ethnic groups. The time-related shift is a reflection of a lesser decrease in the incidence of colorectal adenocarcinoma on the right side than on the left.

CONCLUSIONS

The most attractive hypothesis is that a greater likelihood of prior polypectomy, and thus prevention of more cancers, occurs on the left side than on the right.

Right-side shift of colorectal adenomas with aging

BACKGROUND

Although it is known that right-side colon cancers increase with aging, the location of adenomas according to age has been controversial. Adenomas found at initial colonoscopies may be a mixture of polyps that arose at various earlier ages.

OBJECTIVES

To elucidate the relationship between location and age at which adenomas actually developed.

DESIGN

Prospective cohort study.

SETTING

A large-scale health appraisal institution in Japan.

PATIENTS

A total of 23,444 consecutive, asymptomatic Japanese who underwent total colonoscopy at their annual medical health check-up.

INTERVENTIONS

We analyzed newly developed adenomas after confirmation of the absence of colorectal neoplasms by two serial total colonoscopies.

MAIN OUTCOME MEASUREMENTS

The results of follow-up colonoscopies in 6304 subjects with no colorectal neoplasms at 2 initial colonoscopies were analyzed. The locations were separated into right-side colon and left-side colon from the splenic flexure. The locations of new adenomas found for the first time during the follow-up term were analyzed.

RESULTS

A total of 1472 subjects developed new colorectal adenomas. In 1255 cases with single adenomas, the ratios of number of cases with right-side lesions to that with left-side lesions at the ages of <40 years, 40 to 49 years, 50 to 59 years, 60 to 69 years, and > or =70 years were 1.18, 1.00, 1.29, 1.31, and 1.89, respectively. In 217 cases with multiple adenomas found concurrently, the percentage of cases with adenomas only on the right side at the ages of <40 years, 40 to 49 years, 50 to 59 years, 60 to 69 years, and > or =70 years were 0%, 25%, 34%, 37%, and 63%, respectively.

LIMITATIONS

Small lesions might have been missed even by 2 serial colonoscopies.

CONCLUSIONS

Adenomas on the right-side colon increased with aging.

Mechanisms of microsatellite instability in colorectal cancer patients in different age groups

PURPOSE

The proportion of colorectal cancers located proximal to the splenic flexure increases with age. Colorectal cancers of the microsatellite instability phenotype are preferentially located in the proximal colon. We investigated the location of colorectal cancer with this phenotype in different age groups to determine whether different molecular mechanisms could account for the changes in distribution of colorectal cancers.

METHODS

A representative sample of 230 colorectal cancers from three age groups (<45 years, 60-70 years, >87 years) was selected from a subset of The Upper Midwest Oncology Medical Registries database. Microsatellite instability was determined by polymerase chain reaction using a panel of five microsatellite markers. The presence of new microsatellite alleles at two or more loci was scored as microsatellite instability. Tumors were otherwise considered microsatellite stable. MLH1 and MSH2 expression was determined by immunohistochemistry. Methylation of the MLH1 gene promotor was determined by methylation-specific polymerase chain reaction assay.

RESULTS

The proportion of tumors of the microsatellite instability phenotype was 21 percent in the young group, 15 percent in the middle group, and 33 percent in the old group. More tumors of the microsatellite instability phenotype were proximal compared with microsatellite-stable tumors in all three age groups, but the differences were significant only for the old group. Tumors of the microsatellite instability phenotype in the older group were associated with MLH1 inactivation (24/29 or 83 percent), MLH1 promoter methylation (18/29 or 62 percent), and proximal location (25/29 or 86 percent), while tumors in the young group were associated with MSH2 inactivation (8/18 or 44 percent) and distal location (11/18 or 62 percent).

CONCLUSION

The age-related proximal shift of colorectal cancers is associated with the microsatellite instability phenotype, MLH1 inactivation, and MLH1 promoter hypermethylation.

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.

Influence of Demographics on Colorectal Cancer

The purpose of this study was to examine the influence of race, gender, and age on colorectal cancer cases in our tumor registry between January 1987 and December 2000 and to determine the implications of these factors on screening strategies. Tumors were defined as early (Stage I/II) or late (Stage HI/IV) and proximal or distal (relationship to splenic flexure). Effect of age was examined by stratifying patients into three groups (<50 years, 50–70 years, >70 years). Two time periods (1/87–12/96 and 1/97–12/00) were compared. Significance ( P < 0.05) was determined by univariate and logistic regression analysis. Between January 1987 and December 2000, 1355 patients (M:F, 699:656; mean, 65.9 years) were entered into the tumor registry [998 whites, 357 African Americans (AA)]. The AA population had a significantly higher proportion of females ( P = 0.0001) and patients <50 years ( P = 0.01). The incidence of carcinoma in situ (CIS) was significantly higher in AA ( P = 0.01). African Americans were more likely to present with late disease ( P = 0.05), proximal cancers ( P = 0.05), and well-differentiated tumors ( P = 0.04). In the entire cohort, proximal lesions were significantly larger ( P = 0.002), poorly differentiated ( P = 0.002), and occurred more often in females ( P = 0.03), patients >70 years ( P = 0.04), and patients with family history of colon cancer compared to distal lesions. Proximal migration of tumors occurred in the latter part (1997–2000 compared to 1987–1996) of the study ( P = 0.002). Patients <50 years had a higher incidence of late stage ( P = 0.03) and poorly differentiated tumors ( P = 0.009). The probability for a proximal tumor in an AA female >70 years was 61.9 per cent and in a white male >50 years was 35.1 per cent. Significant differences exist in the stage and location of tumors according to patient's age, race, and gender. These factors should be considered in implementing public screening strategies. Specifically, African-American patients were more likely to present with late-stage tumors, and more aggressive patient education and screening programs should be implemented. For all groups, a proximal migration of colorectal tumors was identified. This factor should eliminate use of sigmoidoscopy as a screening tool. Complete colonoscopy, instead, should be the procedure of choice to identify colonic neoplasia.

Association of older age and female sex with inadequate reach of screening flexible sigmoidoscopy

PURPOSE

Estimates of the sensitivity of screening sigmoidoscopy assume an adequate depth of insertion is reached. However, in clinical practice, the frequency that sigmoidoscopy reaches various lengths of the colon is not known. We assessed the frequency of inadequate reach (depth of <50 cm of the colon) in a large U.S. cohort, according to age and sex.

METHODS

We performed a cross-sectional study of 15,406 asymptomatic persons aged 50 years or older who underwent screening flexible sigmoidoscopy between April 1997 and October 2001 at sites participating in the Clinical Outcomes Research Initiative, which examines outcomes of endoscopy in "real life" settings. The maximum depth of insertion of the sigmoidoscope was measured in centimeters from the anus and classified as adequate (> or =50 cm) or inadequate (< 50 cm). Patient characteristics as well as procedure-related variables were also recorded.

RESULTS

Eighteen percent (n = 2801) of subjects had an inadequate examination. In men, the percentage of inadequate examinations increased progressively with age, from 10% (343/3338) in those aged 50 to 59 years to 22% (53/248) in those aged 80 years or older (P <0.001). Inadequate examinations were more common in women at all ages, ranging from 19% (733/3798) in those aged 50 to 59 years to 32% (86/267) in those aged 80 years or older (P <0.001). These associations were confirmed in a multivariable analysis.

CONCLUSION

Our finding that advancing age and female sex were independently associated with the risk of inadequate reach of screening sigmoidoscopy suggests that the sensitivity of sigmoidoscopy may be lower in these populations. Estimates of the benefits of sigmoidoscopy may need to be tailored to the age and sex of the patient.

Colon cancer during pregnancy

The medical community should become mobilized to diagnose colon cancer earlier in pregnancy to improve prognosis. The primary care physician or obstetrician should refer the pregnant patient with significant gastrointestinal complaints to the gastroenterologist for evaluation. Likewise, the gastroenterologist should be prepared to perform sigmoidoscopy, preferably without endoscopic medications, for significant lower gastrointestinal symptoms such as persistent rectal bleeding. Sigmoidoscopy is particularly sensitive in identifying colon cancer in pregnant patients because their cancers are usually distal and within reach of the sigmoidoscope.

Are there two sides to colorectal cancer?

Colorectal carcinomas (CRC) that arise proximal (right) or distal (left) to the splenic flexure exhibit differences in incidence according to geographic region, age and gender. Together with observations that tumours in the hereditary cancer syndromes HNPCC and FAP occur predominantly in the right and left colon, respectively, the existence of 2 categories of CRC based on site of origin in the large bowel was proposed more than a decade ago. Differences between normal right and left colonic segments that could favour progression through different tumourigenic pathways are summarized in this review. Accumulating evidence suggests that the risk of CRC conferred by various environmental and genetic factors is different for proximal and distal tumours. Right- and left-sided tumours also exhibit different sensitivities to fluorouracil-based chemotherapy. Such differences are probably related to the molecular characteristics of the tumours, with the microsatellite instability and CpG island methylator phenotypes being associated with right-sided tumours and chromosomal instability with left-sided tumours. Future molecular-based classification systems for CRC that rely upon distinctive gene expression patterns may allow a clearer discrimination of subgroups than that provided by tumour site alone. Until then however, the existence of 2 broadly different groups of cancer defined by site of origin in the colon should be considered in the design of future epidemiologic studies as well as in the design of new clinical trials aimed at testing novel adjuvant therapies.

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.

Loss of heterozygosity on chromosome 10q is associated with earlier onset sporadic colorectal adenocarcinoma

Recent studies have shown that loss of heterozygosity (LOH) on chromosome 10q is a frequent event in a number of tumour types including colorectal cancers. Because previous studies have used markers located mainly distally on chromosome 10, we have examined 114 sporadic colorectal adenocarcinomas for LOH using a panel of 9 highly polymorphic microsatellite markers spanning the long arm of chromosome 10. Using microdissected tumour material, LOH of one or more chromosome 10q markers was a frequent event (75 of 114; 66%). The highest frequency of loss (42 of 96; 44%) was observed at the marker D10S1790 located at 10q21.1. The mean age of presentation, of patients with LOH of D10S1790 was significantly (p = 0.0006) lower (67.1 years) compared to patients with retention of this marker (73.5 years). When we compared frequency of loss at this marker in patients presenting before 70 years of age (68%) to those above 70 years (23%) we observed a significant difference (p < 0.0001). Statistical analysis between loss, or instability at other markers and clinicopathological features did not show any significant associations. In addition LOH at D10S1790 was infrequent in adenomas (2 of 20; 10%) compared to adenocarcinomas (42 of 96; 44%) (p = 0.0047), suggesting that loss within this region is a late event in colorectal tumorigenesis. The association of loss at D10S1790 and an earlier age of presentation in adenocarcinomas suggests that this locus may harbor a tumour suppressor gene(s), which affects the rate of colorectal tumour progression. Identification of this region of genetic loss further refines our understanding of the paradigm in this tumour type of multiple-steps responsible for initiation and progression.

Stool screening for colorectal cancer: evolution from occult blood to molecular markers

BACKGROUND

Colorectal cancer is the second leading cause of malignant death, and better preventive strategies are needed. Participation rates for colorectal cancer screening remain low due, in part, to perceived discomfort, potential harm, and high costs with available tools.

METHODS

Stool testing, unlike other conventional screening approaches, is noninvasive and requires no cathartic preparation. However, widely used fecal blood tests yield frequent false-negative and false-positive results that lower screening effectiveness and raise program costs. There is a compelling biological rationale to target DNA alterations exfoliated from neoplasms into stool, and multiple DNA markers would need to be assayed because of the genetic heterogeneity of colorectal neoplasia. Early clinical studies with this multi-target DNA-based stool assay approach suggest high sensitivity for both colorectal cancer and premalignant adenomatous polyps while maintaining high specificity.

CONCLUSIONS

This apparently accurate and user-friendly new approach holds promise to improve the effectiveness, efficiency, and appeal of colorectal cancer screening. Large-scale clinical studies are clearly warranted to corroborate the early results.

Gastrointestinal tract cancer in the elderly

Gastrointestinal cancers are common in the elderly. In the 1990s, modest advances in the early diagnosis, staging, and treatment of gastrointestinal cancers were made. Emphasis has been placed on screening for colorectal cancer; development of new diagnostic and staging modalities, particularly endoscopic ultrasound; and introduction of new treatment regimens, such as chemoradiation programs for esophageal, pancreatic, and colorectal cancers as well as endoscopic mucosal resection of early gastrointestinal cancers. New palliative techniques, such as laser and photodynamic therapy and placement of enteral stents, are being used increasingly in patients who have advanced cancer and are not surgical candidates. In the past, attitudes toward the elderly affected the management of cancer. Age should not be the only parameter considered when addressing the treatment of a gastrointestinal malignancy. Management decisions in the elderly should follow the same principles as those in younger patients. A thorough medical evaluation in the elderly is necessary to evaluate the patient's risk and to optimize surgical, chemotherapeutic, and palliative outcomes.

Predictors of proximal vs. distal colorectal cancers

BACKGROUND

Because proximal colorectal cancers have a tendency to present at a more advanced stage and thus have a poorer prognosis, it is important to understand the factors associated with the development of proximal colorectal cancer. We hypothesized that older age, female gender, and the presence of comorbid illness would be associated with proximal cancers.

METHODS

Incident cases of colorectal cancer (n = 9,550) occurring in 1994 were identified from Florida's population-based statewide cancer registry. We categorized colorectal cancers as either proximal (cecum, ascending colon, and transverse colon) or distal (descending colon, sigmoid colon, rectosigmoid, and rectum). Multiple logistic regression analysis was used to determine the multivariable relationship between clinical characteristics and the odds of a proximal-occurring lesion.

RESULTS

Four characteristics emerged as independent predictors of a proximal lesion. Each year of increasing age was associated with a 2.2 percent increase in the odds of a proximal lesion, whereas female gender was associated with a 38 percent increase in the odds of a proximal lesion. The presence of a comorbid condition was associated with a 28 percent greater odds of a proximal lesion, and, finally, black, non-Hispanic race was associated with a 24 percent greater odds of a proximal lesion.

CONCLUSIONS

We found that increasing age, female gender, black, non-Hispanic race, and the presence of comorbid illnesses were factors associated with a greater likelihood of developing colorectal cancer in a proximal location. Further studies will be required to confirm these findings and to establish the mechanism by which comorbidity influences the site of colorectal cancer development.

Differences between features of adenoma in the rectum versus sigmoid colon

OBJECTIVE

Although the prevalence of cancer in the rectosigmoid is high compared with that in the more proximal colon, the features of cancer developing from an adenoma have yet to be elucidated. The aim of this study is to examine the clinicopathological relationship between cancer and adenoma in the rectosigmoid.

METHODS

A total of 340 adenomas located in the rectosigmoid in 255 patients were retrospectively examined regarding such clinicopathological factors as location and the grade of dysplasia.

RESULTS

The prevalence of adenoma was 102 in the rectum and 238 in the sigmoid colon, respectively, whereas the prevalence of adenoma with high-grade dysplasia was 39 in the rectum and 48 in the sigmoid colon, respectively. This prevalence of adenoma with high-grade dysplasia was thus significantly higher in the rectum than in the sigmoid colon (p < 0.02).

CONCLUSIONS

These findings suggest the possibility of different types of cancer development between adenoma of the rectum and sigmoid colon.

Cancer and adenomatous polyp distribution in the colorectum

OBJECTIVE

To examine the possible role of adenomatous polyps in colorectal cancer development, this study focused on the relationship of the distribution between adenomatous polyps and cancer in the colorectum.

METHODS

The distribution of 753 adenomatous polyps was compared with that of 35 colorectal cancer lesions in 510 male patients ranging from 45 to 55 yr of age who underwent a total colonoscopy.

RESULTS

The incidence of cancer significantly increased with a distal shift in the colorectal sites in comparison with that of adenomatous polyps (p < 0.02).

CONCLUSION

The different distribution between adenomatous polyps and cancer thus suggested that adenomatous polyps at various colorectal sites appear to have a different malignant potential for cancer development.

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.

S-phase fraction and tumor aneuploidy in colorectal carcinoma of young patients

BACKGROUND

Young patients with colorectal carcinomas are considered to have a worse prognosis than older patients. It was the goal of this study to assess if biologic characteristics of tumors in young patients differ from those observed in 2 different groups of patients with the same clinical characteristics but ranging in age either from 41 to 60 years or 61 years and older, respectively.

METHODS

Colorectal carcinoma tumor samples were obtained from storage from patients age 40 years and younger and examined for tumor ploidy and S-phase fraction. For each younger patient, a control was selected among patients matched for Dukes stage, site of primary tumor, and sex, with the two age groups.

RESULTS

Thirty-one of 1361 patients (2.2%) with colorectal carcinoma treated at our institution between 1984 and 1994 age 40 years or younger. Tumor aneuploidy was present in 3 younger patients, in 5 patients in the 41 to 60 years age group, and in 5 patients in the 61 years and older age group. S-phase fraction was 27.67 +/- 13.62 in patients younger than 40 years, 25.35 +/- 11.6 in the 40 to 61 years age group, and 22.45 +/- 8.48 in the 61 years and older age group. These differences were not statistically significant.

CONCLUSIONS

It appears that there are no significant differences in S-phase fraction and tumor aneuploidy in patients younger or older than 40 years, suggesting that colorectal tumors arising in young people do not have different biologic properties.

Increased incidence of proximal colon cancer in the elderly

To define the characteristics of colorectal cancer with regard to site distribution, age, and sex, due to the significantly increased incidence of colorectal cancer in Japan, we investigated 1,205 Japanese patients with colorectal cancer between 1975 and 1994. When we compared site distribution for age and sex in the entire 20-year period, tumors in the proximal colon were more frequent in elderly patients than in young ones (p < 0.05); this tendency was true only for females (p < 0.01), but not for males. The increased incidence of proximal colon cancer in elderly patients was also found in the second 10-year period (p < 0.05). Because elderly patients are characterized by an increasingly high incidence of proximal colon cancer in recent years, more concerted efforts for the early detection of proximal colon cancer, particularly in the elderly, are called for.

Physical activity and risk of colorectal cancer in men and women

We examined the association between self-reported occupational and recreational physical activity and the subsequent risk of colorectal cancer in a population-based cohort in Norway. During a mean follow-up time of 16.3 years for males and 15.5 years for females, 236 and 99 colon cancers and 170 and 58 rectal cancers were observed in males and females, respectively, among 53,242 males and 28,274 females who attended the screening between 1972 and 1978. Physical activity at a level equivalent to walking or bicycling for at least four hours a week during leisure-time was associated with decreased risk of colon cancer among females when compared with the sedentary group (RR = 0.62, 95% CI 0.40-0.97). Reduced risk of colon cancer was particularly marked in the proximal colon (RR = 0.51, 95% CI 0.28-0.93). This effect was not observed for occupational physical activity alone, probably due to a narrow range of self-reported physical activity at work among females. However, by combining occupational and recreational physical activity we observed an inverse dose-response effect as increasing total activity significantly reduced colon cancer risk (P for trend = 0.04). Among males 45 years or older at entry to the study, an inverse dose-response effect was observed between total physical activity and colon cancer risk (P for trend = 0.04). We also found in males a stronger preventive effect for physical activity in the proximal as compared to distal colon. In addition, we found a borderline significant decrease in colon cancer risk for occupational physical activity in males 45 years or older when compared to the sedentary group (RR = 0.74, 95% CI 0.53-1.04). All results were adjusted for age, body mass index, serum cholesterol and geographic region. No association between physical activity and rectal cancer was observed in males or females. The protective effect of physical activity on colon cancer risk is discussed in regard to energy balance, dietary factors, age, social class, body mass index and gastrointestinal transit time.

A national population-based study of incidence of colorectal cancer and age. Implications for screening in older Americans

BACKGROUND

Population-based screening programs with flexible sigmoidoscopy have been advocated as a means to reduce the death rate from colorectal cancer. Because other studies have suggested a greater prevalence of lesions inaccessible to sigmoidoscopy in older patients, the expected yield of this procedure may differ in these subgroups.

METHODS

A 100% sample of Medicare beneficiaries 65 years or older with a first known diagnosis of colorectal cancer in 1987 was studied. Tumor site was divided into rectum, distal colon (distal to splenic flexure) and proximal colon. The analysis was also stratified by sex, race, and presence or absence metastatic disease, and incidence rates at each site by 5-year age group were calculated.

RESULTS

Among the 75,266 patients studied, the incidence of colorectal cancer increased from 1.59 patients/1000 in patients age 65-69 years to 3.87 patients/1000 in patients age 85 years and older. Although the incidence rates at all three sites increased, the increment was greatest for proximal tumors. The incidence trends with age also persisted in an analysis of only metastatic lesions. Moreover, incidence rates were consistently higher in men than in women and higher in whites than in blacks at all sites, though the age-related increase in incidence was consistent among all four groups.

CONCLUSIONS

The proportion of tumors beyond the reach of sigmoidoscopy increased with age, as did the actual incidence of accessible lesions. These patterns were also consistent in subgroup analyses. As the age-related increase in incidence was observed for metastatic tumors at all sites in the colon, age-related differences in screening and diagnostic evaluation alone do not adequately explain the findings. These data underscore the need for further studies of the relative benefits of cancer screening and pathogenic factors in tumor development in different subgroups of the older population.

Colorectal carcinoma: analysis of management in two medical eras

Trends in presentation, diagnosis, management, and outcome were analyzed for 503 patients with colorectal cancer seen at the UCLA Medical Center between 1960 and 1970 (Group A; n = 210) and 1980 and 1985 (Group B; n = 293). Patients in the latter group exhibited a shift in site to the right side of the colon (18% in Group A vs. 31% in Group B; P < .01), an increase in the number of primary resections without colostomy (38% vs. 61%; P < .01), a lower overall complication rate (28% vs. 18%; P = .01), and a decline in 30-day mortality (6.2% vs. 2%; P = .01). Although little difference was seen in detection of asymptomatic tumors, earlier lesions were treated in the latter group, accounting for substantially reduced rate of recurrence (69% in Group A vs. 44% in Group B; P < .01). Future management should include an emphasis on earlier detection in order to continue the trend toward enhanced survival.

Metabolic phenotypes and colorectal neoplasia

It now appears likely that the development of colonic adenomas and carcinomas involves a series of steps in which environmental or endogenous carcinogens induce or promote neoplasia through the accumulation of multiple, specific genetic mutations. Genetic predisposition to this process may take the form of inherited defects in control of cellular proliferation as in familial polyposis coli, or genetically determined polymorphism which affects enzyme activities relevant to the production or detoxication of carcinogens. Genetic effects may also influence levels of hormones and/or their target cell receptors which regulate the metabolic and proliferative activity of colonocytes. This review highlights data suggesting a role for polymorphism associated with xenobiotic acetylation, hydroxylation, and conjugation with glutathione in the metabolism of potential carcinogens, as well as for dehydroepiandrosterone in the metabolic control of cell proliferation. The study of genetically determined polymorphism in colorectal cancer may provide new insights into the epidemiology of cancer and result in new methods for the detection of higher risk groups.