Colonoscopy screening reduces the risk of advanced colorectal cancer by about 70% in average-risk adults.

The finding came from a new study led by a researcher at the Perelman School of Medicine at the University of Pennsylvania and was published in the journal Annals of Internal Medicine.

The research provides proof to current medical suggestions that people of average-risk can reduce their probability of being diagnosed with advanced colorectal cancer (CRC) in either the right or left side of the colon after receiving a screening colonoscopy.

Colonoscopy has started to quickly take the place of sigmoidoscopy in recent years, even though it costs more and there was only little evidence of its success at first. Sigmoidoscopy is a procedure which identifies abnormalities in the rectum and left side of the colon.

The current report demonstrated an overall 70% decrease of late-stage CRC diagnoses linked to receiving a screening colonoscopy.

This indicates, according to the authors, that colonoscopy can successfully detect tumors in both the left and right side of the colon before progressing to an advanced stage.

Prior studies have shown that screening with sigmoidoscopy or fecal occult blood test reduces the likelihood of dying from colorectal cancer.

However, the effectiveness of the colonoscopy, which inspects for precancerous and cancerous growths throughout the whole colon, has been mostly unknown in average-risk men and women.

The efficacy of colonoscopy’s in the right colon has remained uncertain, despite the fact that it is where about 50% of novel CRC cases in the U.S. are found.

Colorectal cancer is one of the most critical cancers people encounter in the U.S., explained lead author on the study Chyke Doubeni, MD, MPH, presidential associate professor of Family Medicine and Community Health at Penn Medicine.

More than 50,000 people died as a result of the disease in 2012, and sadly, Doubeni pointed out, the majority of those deaths are preventable through:

  • screening
  • early detection
  • treatment

“Our goal with this study was to understand the extent to which colonoscopy can prevent the diagnosis of advanced colorectal cancers, the ones that primarily result in death. What we saw was a dramatically reduced risk of death for patients who were screened,” Doubeni said.

Even though the prevalences of CRC and cancer-associated deaths are going down, CRC is still the third most common cancer around the world and the second main cause of cancer deaths.

A study from last year said that the use of colonoscopy for colorectal cancer screening may be responsible for the significant reduction in the cancer’s incidence over the past 10 years.

Knowing the effectiveness of screening colonoscopy needs to be explained more widely. Expertts say the procedure is underused.

Michael Kochman, MD, Wilmott Family Professor of Medicine and co-director of the Gastrointestinal Oncology Program at Penn Medicine, explained:

“Screening colonoscopy is used to look for early growths which may turn into cancer by allowing physicians to see any polyps or bleeding in the colon or rectum. If any abnormalities – such as polyps – are detected, the physician can remove all or part of them with biopsy techniques during the procedure, making it a very effective means of spotting and removing potentially cancerous growths.”

The investigators assessed data from four U.S. managed care organizations that form part of the HMO Cancer Research Network for the purpose of their case-control study.

The scientists wanted to look at how successful colonoscopies are in preventing late-stage colorectal cancer diagnoses.

Medical records for 1,012 average-risk individuals between the ages of 55 and 85 were exmined. A total of 474 patients had advanced colorectal cancer – 251 of whom (54%) had tumors in the right side of the colon.

In those cases, sigmoidoscopy would not have been a successful procedure for screening.

In order to help experts understand more about the efficacy of colonoscopy, randomized trials are currently being conducted. Unfortunately, it will be many years until their results are known.

Robert H. Fletcher, MD, MSc, professor emeritus at Harvard Medical School and co-author on the study, concluded:

“The results of this study confirm the effectiveness of screening colonoscopy and reinforce the importance of the procedure for all adults over the age of 50. As we wait to learn more about the effectiveness of screening colonoscopy through clinical trials, this case-control study provides credible answers that support current screening practices and recommendations.”

Written by Sarah Glynn