What: After reporting lackluster third quarter financial results that led to its shares falling by 13% yesterday, shares in Exact Sciences (NASDAQ:EXAS) are rebounding by more than 10% today.

So what: Exact Sciences makes Cologuard, a colon cancer screening test that can help doctors determine which patients may benefit most from a colonoscopy.

Cologuard launched last fall to high expectations stemming from an ongoing need to improve colon cancer screening. Although colon cancer can be treated successfully when identified early, many people avoid or delay screening because other screening methods can be intrusive.

So far, however, Cologuard's sales have been materialized more slowly than some have hoped. For example, the company completed 21,000 tests generating just $8.1 million in revenue during the second quarter of this year.

In part, Cologuard's disappointing growth is due to delays in negotiating reimbursement with payers, such as insurers, some of which were awaiting colon cancer screening guidelines. Earlier this month, a draft of these guidelines was released that didn't award Cologuard with an "A" or "B" rating that could have forced the hands of insurers.

Regardless, the company's third quarter results do suggest that the company is making headway in winning over doctors and payers. Exact Sciences reports it completed 34,000 Cologuard tests in the third quarter, up 62% from Q2, and that sales reached $12.6 million in Q3.

Unfortunately, Exact Sciences spending on marketing and infrastructure supporting Cologuard more than offset this bump up in volume and revenue as operating expenses of $48.4 million led to a net loss of $42.9 million, or -$0.45 per share last quarter.

Now what: There's no question that doctors and patients need new weapons to battle colon cancer and clearly Cologuard's use is increasing, but investors have to balance those demand drivers against the fact that Exact Sciences expenses are massive and its losses aren't likely to disappear anytime soon.

Having said that, Exact Sciences conference call does suggest that there's a chance that Cologuard gets backed in the finalized screening guidelines, which could boost volume, and since Exact Sciences shares have fallen from over $30 earlier this year to their current levels around $8, its $774 million market cap is far more reasonable to its sales run rate than it was in June.

Nevertheless, it's unclear to me when this company could turn a profit and for that reason, I'll be sitting on the sidelines until Exact Sciences proves itself.