Screening for colorectal carcinoma

Equity and practice issues in colorectal cancer screening: Mixed-methods study

OBJECTIVE

To investigate overall colorectal cancer (CRC) screening rates, patterns in the use of types of CRC screening, and sociodemographic characteristics associated with CRC screening; and to gain insight into physicians' perceptions about and use of fecal occult blood testing [FOBT] and colonoscopy for patients at average risk of CRC.

DESIGN

Mixed-methods study using cross-sectional administrative data on patient sociodemographic characteristics and semistructured telephone interviews with physicians.

SETTING

Toronto, Ont.

PARTICIPANTS

Patients aged 50 to 74 years and physicians in family health teams in the Toronto Central Local Health Integration Network.

MAIN OUTCOME MEASURES

Rates of CRC screening by type; sociodemographic characteristics associated with CRC screening; thematic analysis using constant comparative method for semistructured interviews.

MAIN FINDINGS

Ontario administrative data on CRC screening showed lower overall screening rates among those who were younger, male patients, those who had lower income, and recent immigrants. Colonoscopy rates were especially low among those with lower income and those who were recent immigrants. Semistructured interviews revealed that physician opinions about CRC screening for average-risk patients were divided: one group of physicians accepted the evidence and recommendations for FOBT and the other group of physicians strongly supported colonoscopy for these patients, believing that the FOBT was an inferior screening method. Physicians identified specialist recommendations and patient expectations as factors that influenced their decisions regarding CRC screening type.

CONCLUSION

There was considerable variation in CRC screening by sociodemographic characteristics. A key theme that emerged from the interviews was that physicians were divided in their preference for FOBT or colonoscopy; factors that influenced physician preference included the health care system, recommendations by other specialists, and patient characteristics. Providing an informed choice of screening method to patients might result in higher screening rates and fewer disparities. Changes in policy and physician attitudes might be needed in order for this to occur.

The complexity of the count: considerations regarding lymph node evaluation in colorectal carcinoma

In patients with colorectal carcinoma, studies have reported improved survival with increasing numbers of retrieved lymph nodes. These findings are puzzling, as increased node sampling was not correlated with significant change in disease staging. Although the physiologic processes underlying this correlation between number of lymph nodes sampled and survival remain unknown, the reported correlation has caused modifications to clinical and non-clinical practices. Herein, we review the literature and discuss potential etiologies responsible for the observed increased survival statistics. Literature regarding colorectal lymph node anatomy, molecular aspects of colorectal cancer, changes in tumor characteristics and utilization of lymph node sample numbers are evaluated. In addition, we present the mathematical concepts available for probabilistic prediction of diagnostic confidence based upon sample size. From evaluation of the aggregate literature, certain facts emerge which are not easily identified within the individual studies. Colorectal carcinoma appears to encompass a number of individual disease entities with different physiologic characteristics and likelihoods of metastasis. In addition, it appears the improved survival is likely multifactorial including effects from intrinsic tumor biology and tumor-host interactions along with ever changing clinical practices. Finally, because lymph node count is dependent on a number of variables and is correlated, but unlikely to be causally associated with survival, use of this number as a quality indicator is unwarranted. Based on statistical considerations, the current recommended goal of 12-15 recovered lymph nodes without evidence of metastatic disease provides approximately 80% negative predictive value for colorectal carcinoma metastasis.