Shares of Exact Sciences (EXAS) are up over 20% today. The maker of Cologuard, a colon cancer DNA screening test, preannounced earnings which handily beat Wall Street’s expectations.

There may be more upside from here, says Hedgeye Healthcare analyst Tom Tobin (he’s been bullish on the stock since last summer). Exact Sciences has thus far undersold the benefits of Cologuard.

Here’s a brief rundown of the quarter.

Exact Sciences added 9,500 new physicians who were recommending Cologuard in the fourth quarter, an increase of +120% year-over-year. That was enough to help beat quarterly revenue numbers, posting $35.1 million or growth of 114% year-over-year. EXAS closed out 2016 with 244,000 tests ordered, of which 82,000 occurred in 4Q16 compared to their guidance of 78,000.

“There’s still a large untapped market opportunity in terms of prescribing physicians” for Exact Sciences, Tobin says in the video above. Our Healthcare team’s analysis suggests that Cologuard is now just 20% penetrated into its total addressable provider market.

“We think the marketing opportunity here and execution opportunity here could be big, given that [Cologuard] tests are pretty good and we’ve got a lot of good feedback from physicians,” Tobin says.