Optimal techniques more efficient than conventional histopathology at identifying pre-cancerous polyps

11 Nov 2009

Optical diagnosis is a reliable method of correctly diagnosing small colorectal polyps during routine colonoscopy and could be a more efficient and cost effective alternative to conventional histopathology. As such, optical diagnosis could replace formal histopathology for the diagnosis and management of most small polyps in routine clinical practice, according to research published in The Lancet Oncology.

Colorectal cancer is the second leading cause of cancer death in developed countries, but when detected early has one of the highest cure rates. The aim of screening programmes for colorectal cancer is the detection and removal of pre-cancerous polyps.

New optical technologies that use white-light colonoscopy (WLC), non-magnifying narrow-band imaging (NBI), and chromoendoscopy have enhanced the ability to diagnose and manage small polyps seen at routine colonoscopy dispensing with the need for formal histopathology—which is time consuming, resource intensive, and results in delays in giving patients advice on future cancer risk and screening intervals.

It has been suggested that these optical technologies could make colonoscopy more efficient and cost effective and have the potential to save an estimated $95 million each year in histopathology costs in the USA alone.
To confirm the efficiency, safety, and clinical benefit of these simple and widely available optical techniques, Ana Ignjatovic and colleagues from St Mark’s Hospital and Imperial College London compared the diagnosis of 363 small colorectal polyps (<10mm) in 130 patients, evaluated by four colonoscopists with different levels of experience, using both optical diagnosis (WLC, NBI, and chromoendoscopy) and histopathology. The authors also assessed the accuracy of optical diagnosis at predicting a patient’s future cancer risk and advice on screening intervals.

Overall, optical diagnosis accurately identified up to 93% of small colorectal polyps (186 of 198 precancerous adenomas and 55 of 62 hyperplastic polyps), similar to the overall diagnostic accuracy of standard histopathology. Expert colonoscopists had an accuracy of 95% for optical diagnosis and non-expert colonoscopists 87%.

In addition, optical diagnosis enabled 82 of the 130 patients to be given a follow-up colonoscopy date immediately after the procedure, providing an estimated saving of £6560 in follow-up clinical appointments. Findings also showed that advice on screening intervals was the same after histopathology and optical diagnosis for 78 of 82 patients (95%).

The authors estimate that replacing histopathology with optical diagnosis in routine clinical practice would have resulted in an overall saving of 77% or £13 343 ($22 000) for the patients in this study.
They say: “We have shown that optical diagnosis, mainly using white light and non-magnified NBI, is accurate for characterisation of polyps smaller than 10 mm...and seems acceptable across a range of experience.”
They conclude: “The short learning curve for NBI…supports early adoption, even outside academic centres. As NBI equipment and experience becomes widespread, optical diagnosis for small colonic polyps could become acceptable standard of care in routine non-academic clinical practice.”

Source: Lancet Oncology