The National Bowel Cancer Screening Program (NBCSP) aims to reduce the incidence, illness and mortality related to bowel cancer in Australia through screening to detect cancers and pre-cancerous lesions in their early stages, when treatment will be most successful.

The NBCSP has been running since August 2006, and this report focuses on measures of program performance for people invited to screen (currently those turning 50, 55 or 65) between July 2011 and June 2012.

How many 2011-12 invitees participated in the NBCSP?

About 35% of the 930,000 people invited between July 2011 and June 2012 returned a completed bowel cancer screening kit for analysis. This overall participation rate was slightly lower than that of the previous monitoring report (Table 1), and evident for all 3 target age groups. The lower rate of participation may be a consequence of the pause in the program between January and June 2011 (Table S1.3) leading to uncertainty over program continuation and reduced participant confidence. The NBCSP recommenced gradually from 1 July 2011 following the Australian Government's decision in the 2011-12 Budget to make the program ongoing.

How many positive screening results were there?

About 22,500 participants (7.0%) who returned a valid screening test had a positive screening result. These people were encouraged to follow up this result by visiting their primary health care practitioner (PHCP) and having further investigative testing (colonoscopy). Seventy-two per cent of those with a positive screening result were recorded as having had a colonoscopy.

How many bowel cancers and adenomas were detected?

One participant in every 32 who underwent a colonoscopy to follow up a positive screening result was diagnosed with a confirmed (68 participants) or suspected (336 participants) cancer, while advanced adenomas were found in a further 857 participants (1 in 15 colonoscopies) assessed. Adenomas are benign growths that have the potential to become cancerous, and their removal is likely to lower the risk of future bowel cancers in these patients.

Were there differences between subgroups participating in the NBCSP?

As in previous years, women were more likely to screen than men; conversely, men had higher rates of screen-detected bowel cancers, and overall bowel cancer incidence and mortality.

Aboriginal and Torres Strait Islander participants, participants who lived in Regional and Remote regions, and participants who lived in areas of lower socioeconomic status, had higher rates of positive screening results, yet lower rates of follow-up colonoscopies than other participants.