Pfizer reported better-than-expected earnings Tuesday, as strong sales in oncology and vaccines offset a hit from patent expirations.

The pharma giant reported third-quarter earnings of $2.1 billion, down 20.1 percent from the year-ago period.

Revenues were $12.09 billion, down 2.2 percent from the year-ago period, in part due to the impact from the strong dollar.

Pfizer notched strong sales gains in its innovative products business, which includes global vaccines and global oncology, two divisions with strong increases.

Other outperformers included global sales of the stroke-reduction drug Eliquis, US sales of Lyrica, which is used to treat nerve pain, and of the rheumatoid arthritis drug Xeljanz in the US.

On the downside, sales for Pfizer's other major division, established products, fell 16.3 percent from the year-ago period to $5.2 billion.

The decline was partly due to the loss exclusivity for some key drugs, including pain-killer Celebrex and the antibiotic Zyvox.    

"Our research pipeline continues to advance with a focus on therapeutic areas of high unmet need," said Pfizer chief executive Ian Read, adding that recent advances "could support the development of potential important new therapies to further strengthen our innovative products business."

Adjusted earnings for the third quarter translated to 60 cents per share, better than the 51 cents analyst estimate. Revenues also topped the $11.56 billion analyst estimate by about $530 million.

Pfizer raised some of its 2015 forecasts, including its 2015 sales to $47.5-$48.5 billion and adjusted earnings of $2.16-$2.20.

The prior estimates were for sales of $46.5-$47.5 billion and adjusted earnings of $2.04-$2.10 per shares.

Shares of Dow member Pfizer rose 3.1 percent to $35.22 in pre-market trade.