Colorectal Cancer Prevention

Colorectal cancer (CRC) is the third most common form of cancer and the second leading cause of cancer-related death in the United States.  The lifetime risk of developing colorectal cancer is 5.5% for men and 5.1% for women.  Fully three-quarters of those diagnosed lack a family history or conditions that predispose to CRC.

While genetic factors cannot be modified, risk reduction in CRC is possible.  High levels of physical activity mitigate the likelihood of developing CRC by as much as 50%, and even sedentary individuals who begin modest exercise later in life may benefit.  Central obesity, Type 2 Diabetes, and especially full-blown Adult Metabolic Syndrome increase risk.  CRC is also a tobacco-related neoplasm; long term smoking is associated with a chance of developing cancer and advanced adenomas equal to that seen with a first degree relative with CRC.

In addition to a healthier lifestyle, a diet low in red and processed meat and rich in fruits and vegetables may be preventive.  Alcohol in excess of 30 gm a day is harmful.  Calcium 1200 mg a day confers very modest risk reduction whereas other forms of chemoprevention, such as ASA/NSAIDs and post-menopausal hormone replacement therapy, are unacceptable from a risk:benefit analysis.

The removal of adenomatous polyps by colonoscopy remains the single best means of CRC prevention.  The National Polyp Study of 1993 suggested a 76-90% reduction in mortality following a "clearing" colonoscopy which persisted for ten or more years.  Although subsequent studies have failed to reproduce this level of benefit, the incidence of CRC over time has been declining rapidly since 1998, by as much as 1.6% per year, largely due to the widespread adoption of screening colonoscopy.

Equally important is the early detection of frank malignancy, and the sensitivity and specificity of colonoscopy for CRC surpasses all other available screening modalities.  Survival benefit here cannot be overemphasized: 90% at five years for local-stage disease; 68% for regional involvement; and only 10% if distant metastases are present.  Fortunately, improved screening measures have been paralleled by significant advances in adjuvant therapy that have reduced CRC mortality by 30% since the late 1980's.

Although still considered the gold standard for CRC screening, the reputation of colonoscopy has been tarnished of late.  A recent study out of Ontario shows a mortality reduction only for left-sided CRC; however, the majority of these examinations were performed by surgeons and general internists rather than gastroenterologists.  In another interesting report from closer to home, twelve expert GI in Rockford, IL, all involved in a training program, were found to have a tenfold difference in adenoma detection, which directly correlated with time spent in cecal extubation.  The latest challenge for endoscopists is non-polypoid colorectal neoplasms, so called flat/depressed adenomas, which may be highly dysplastic, hard to detect and remove, and represent up to 6% of all polyps.  These lesions, far more common proximally, may represent changing tumor biology and likely explain, at least in part, "missed cancers" occurring prematurely after colonoscopy.

There are geographic differences in the incidence of CRC, with overall lower rates in the western U.S. and higher in the southern states and the Midwest.  In 2006 the Iowa Department of Public Health and the University of Iowa College of Public Health surveyed CRC in our state.  At the time of publication, only 43% of Iowans age fifty and above with this malignancy had been diagnosed with early-stage disease.  The significance of this has already been stated, and they concluded that 30% of these deaths over the past quarter century could have been prevented through colonoscopic screening.  Furthermore, saving the lives of Iowans could be cost-effective; using 2001 actuarial data a white male age fifty or older would save $41,530 for each year of life free of CRC by undergoing colonoscopy every ten years.

In Goals for Healthy Iowans 2010 better statewide CRC screening is targeted; an outgrowth of this is a grant from the Iowa Department of Public Health to St. Luke's Hospital that directly benefits needy citizens of Eastern Iowa.  Those age fifty and older with incomes below 250% of federal poverty guidelines are eligible for screening colonoscopy at no charge with grant monies used to offset provider losses.  Sixty qualified individuals will be screened in the initial stage, and, despite present economic conditions, the grant has just been renewed.  If you are a patient in need of screening who might meet selection criteria, please contact  (319) 558-4867.

Click here to Schedule your Screening Colonoscopy.