Screening for colorectal cancer--now and the near future

Non-steroidal anti-inflammatory drugs and biomarkers: A new paradigm in colorectal cancer

Colorectal cancer is a sporadic, hereditary, or familial based disease in its origin, caused due to diverse set of mutations in large intestinal epithelial cells. Colorectal cancer (CRC) is a common and deadly disease that accounts for the 4^th worldwide highly variable malignancy. For the early detection of CRC, the most common predictive biomarker found endogenously are KRAS and ctDNA/cfDNA along with SEPT9 methylated DNA. Early detection and screening for CRC are necessary and multiple methods can be employed to screen and perform early diagnosis of CRC. Colonoscopy, an invasive method is most prevalent for diagnosing CRC or confirming the positive result as compared to other screening methods whereas several non-invasive techniques such as molecular analysis of breath, urine, blood, and stool can also be performed for early detection. Interestingly, widely used medicines known as non-steroidal anti-inflammatory drugs (NSAIDs) to reduce pain and inflammation have reported chemopreventive impact on gastrointestinal malignancies, especially CRC in several epidemiological and preclinical types of research. NSAID acts by inhibiting two cyclooxygenase enzymes, thereby preventing the synthesis of prostaglandins (PGs) and causing NSAID-induced apoptosis and growth inhibition in CRC cells. This review paper majorly focuses on the diversity of natural and synthetic biomarkers and various techniques for the early detection of CRC. An approach toward current advancement in CRC detection techniques and the role of NSAIDs in CRC chemoprevention has been explored systematically. Several prominent governing mechanisms of the anti-cancer effects of NSAIDs and their synergistic effect with statins for an effective chemopreventive measure have also been discussed in this review paper.

Positron emission tomography for benign and malignant disease

Functional imaging using radiolabeled probes that specifically bind and accumulate in target tissues has improved the sensitivity and specificity of conventional imaging. Fluorodeoxyglucose (FDG)-positron emission tomography (PET) has shown improved diagnostic accuracy in differentiating benign from malignant lesions in the setting of solitary pulmonary nodules. FDG-PET has become useful in preoperative staging of patients with lung cancer, and is being tested with many other malignancies for its ability to change patient management. This article provides an overview of the current status of FDG-PET and presents the challenges of moving toward routine use.

Serum soluble mesothelin concentrations in malignant pleural mesothelioma: relationship to tumor volume, clinical stage and changes in tumor burden

PURPOSE

To examine the clinical utility of soluble mesothelin in patients with malignant pleural mesothelioma.

EXPERIMENTAL DESIGN

A total of 97 patients (female: 11; male: 86) were prospectively enrolled, longitudinal serum samples collected, and mesothelin concentrations determined. Baseline mesothelin levels were analyzed relative to tumor stage, presence of metastatic disease, the positron emission tomography (PET) parameters maximum standardized uptake value, tumor volume, total glycolytic volume, and survival. Changes in mesothelin level were correlated to objective response to chemotherapy, as assessed radiologically and by PET imaging, and with patient survival.

RESULTS

Baseline mesothelin levels greater than 5 nmol/L were a significant negative prognostic indicator (HR = 2.25; 95% CI, 1.20-4.21) and correlated with tumor stage and volume. In 55 patients who received chemotherapy, change in mesothelin correlated with radiological response (χ(2) = 11.32; P = 0.023) and change in metabolically active tumor volume (r = 0.58; P < 0.01). Median survival for patients with a reduction in mesothelin following chemotherapy (19 months) was significantly longer than for patients with increased mesothelin (5 months; P < 0.001).

CONCLUSION

These findings show the potential value of changes in mesothelin levels for prognostication and monitoring of treatment response in mesothelioma.

Colonography by CT, MRI and PET/CT combined with conventional colonoscopy in colorectal cancer screening and staging

Colorectal cancer (CRC) remains a leading cancer killer worldwide. But the disease is both curable and preventable at an early stage. Regular CRC cancer screening has been shown to reduce the risk of dying from CRC. However, the importance of large-scale screening is only now starting to be appreciated. This article reviews a variety of imaging procedures available for detecting ulcerative colitis (UC) and Crohn’s disease (CD), polyps and CRC in their early stage and also presents details on various screening options. Detecting, staging and re-staging of patients with CRC also require multimodality, multistep imaging approaches. Staging and re-staging with conventional colonoscopy (CC), computer tomography colonography (CTC), magnetic resonance colonography (MRC) and positron emission tomography/computer tomography colonography (PET/CTC) are of paramount importance in determining the most appropriate therapeutic method and in predicting the risk of tumor recurrence and overall prognosis. The advantages and limitations of these modalities are also discussed.

Free DNA and carcinoembryonic antigen serum levels: an important combination for diagnosis of colorectal cancer

PURPOSE

The identification of new molecular markers for the early detection of colorectal cancer has become an important objective. We compared the sensitivity and specificity of free circulating DNA with that of the more conventional carcinoembryonic antigen (CEA) and evaluated the two markers in combination.

EXPERIMENTAL DESIGN

The study was carried out on 75 healthy donors and 75 colorectal cancer patients. Free DNA was determined in serum with quantitative PCR analysis. The diagnostic accuracy of each assay was calculated using receiver operating characteristic (ROC) curves. The diagnostic relevance of the two-marker combination was analyzed by the logistic regression model.

RESULTS

Median free DNA concentration was approximately 5-fold higher in patients than in healthy donors (P < 0.001). The area under the ROC curve was 0.86, and when 12.5 ng/mL was used as cutoff, 81.3% sensitivity and 73.3% specificity were observed for the overall series. As CEA and free DNA provided independent diagnostic information, they were also considered in combination. ROC curve analysis of the combined CEA and free DNA algorithms showed a higher diagnostic capacity (area under the ROC curve, 0.92) than that of markers considered singly, with 84% sensitivity and 88% specificity.

CONCLUSIONS

Free circulating DNA, especially when used in combination with CEA, represents a potentially useful tool for the diagnosis of early-stage colorectal cancer.

Detection of Malignant Mesothelioma in Asbestos-Exposed Individuals: The Potential Role of Soluble Mesothelin-Related Protein

Malignant mesothelioma (MM) is strongly associated with asbestos exposure. Measurement of soluble mesothelin-related protein (SMRP) levels in the serum may prove valuable as an adjunct to current tests for the diagnosis of MM and for monitoring MM patients for the early detection of disease recurrence. SMRP measures also may be useful in an overall screening program for MM because early results show that some individuals have elevated levels 1 to 4 years before symptom development. Although individuals with occupational and nonoccupational asbestos exposure are justifiably concerned about their risk of developing MM, consideration must be given to the complex issues surrounding screening for this disease, and a more substantial evaluation of the SMRP marker must be undertaken before deciding to promote a screening program.

Colorectal cancer screening behavior in women attending screening mammography: Longitudinal trends and predictors

PURPOSE

Nationally representative surveys demonstrate that the adherence to screening mammography guidelines are associated with increased prevalence of colorectal cancer (CRC) screening; however, the incidence of CRC screening in the screening mammography population is unknown. Our purpose was to describe non-fecal occult blood test (FOBT) CRC screening utilization by women prior to and subsequent to screening mammography at a large academic medical center.

MATERIALS AND METHODS

Using the institutional administrative data base, 17,790 women aged 50 and older who underwent screening mammography between 1998 and 2002 were retrospectively identified. We determined that women were current with non-FOBT CRC screening at the time of mammography if they had undergone flexible sigmoidoscopy or double-contrast barium enema in the 5 years or colonoscopy since 1995, the earliest for which data are available. We excluded FOBT as a form of CRC screening because the administrative data base did not adequately capture episodes of FOBT. Women who were not current were considered eligible for non-FOBT CRC screening. We then assessed the number of women who underwent flexible sigmoidoscopy, barium enema, or colonoscopy within 12 months following mammography. Age, insurance status, Breast Imaging Reporting and Data System classification, recommendations after screening mammography and year of mammography were examined as potential predictors of non-FOBT CRC screening completion.

RESULTS

At the time of mammography, 13.3% women were current with non-FOBT CRC screening. Of women eligible for non-FOBT CRC screening at the time of mammography, 1.1% completed non-FOBT CRC screening within 12 months after mammography. The rate of non-FOBT CRC screening completion increased over time. After multivariate analysis, being insured by a commercial managed care organization or by Medicaid remained significant predictors of non-FOBT CRC screening.

CONCLUSION

The prevalence of non-FOBT CRC screening is low in the population of women undergoing screening mammography, with an incidence of 1.0%. Future studies should examine whether delivering CRC screening interventions at a screening mammography visit increase adherence to non-FOBT CRC screening.