Disease Extension in UC and UP
The inflammation in ulcerative colitis (UC) and ulcerative proctitis (UP) is dynamic and the extent of the colon involved can change over time. UC and UP uniformly affect the rectum (the lowest part of the colon) and the inflammation extends for a variable length upwards through the colon. Studies of UP patients suggest that the disease moves further up to involve more of the colon in about 25% of patients after diagnosis. The probability of disease extension appears to increase over time, with cumulative probabilities of extension estimated to be 20% and 55% at 5 and 10 years, respectively. Why the amount of colon involved remains stable in some patients and extends over time in others is not known. Risk factors for extension of disease include severe, and poorly controlled UP and UC. It is noteworthy that extension of disease can occur even in patients who are asymptomatic. Understanding the anatomic location of inflammation in the colon is important because we know that segments that have been inflamed are at greater risk of developing cancer than uninflammed segments. As such, taking medications as prescribed and staying on schedule for colon cancer screening are important for UP and UC patients.