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It's a sleepy day on the markets, with the Dow Jones Industrial Average (DJINDICES:^DJI) slumbering in the red this morning before groggily moving into the green this afternoon. The Dow has gained about 23 points as of 2:35 p.m. EDT, with few big movers among the index's blue-chip stocks. Health care's biggest names haven't budged much today, with Johnson & Johnson (NYSE:JNJ) up about 0.5% and rival Pfizer (NYSE:PFE) at breakeven.

However, these two companies are dueling for more than just day-to-day stock movements. One area that has become critical to Pfizer, Johnson & Johnson, and other pharmaceutical players is cancer-fighting drugs -- and these two companies are among the industry's best at developing them.

The battle for the cancer drug market
Pfizer's recent third-quarter earnings showed just how much its oncology division means. The company's cancer-fighting segment has produced recent high-growth drugs like Xalkori, which saw revenue almost double this quarter. The drug's still recording small sales right now after being approved just two years ago, but analysts think this treatment could one day hit $2.5 billion or more in peak annual sales -- enough to make it one of Pfizer's top-selling pharmaceutical products.

Overall, Pfizer's oncology unit hit 24% revenue growth year over year in its recent earnings report, even though the division only sold about $400 million for the quarter -- a little more than a third of the total quarterly sales from top-selling Pfizer pain therapy Lyrica. Lyrica's still growing strongly with more than 9% sales growth this quarter, but oncology's rapid growth means this drug will have company down the line among Pfizer's best-selling medications. Pfizer's Inlyta, another oncology drug that's working on driving sales higher, almost tripled its revenue year over year for the quarter.

Johnson & Johnson isn't content to let its rival take the lead in this sector, however. The company's own oncology treatments have hit high marks lately, and they're primed for further growth as this market grows.

Johnson & Johnson's total pharmaceutical sales jumped by nearly 10% for the quarter, making the division the company's largest by revenue, ahead of its medical-devices division. Prostate cancer drug Zytiga has shined for Johnson & Johnson investors. The drug came through with strong growth again in the third quarter after recording more than 70% year-over-year growth through the first half of 2013. Zytiga's on pace to exceed blockbuster status of $1 billion or more in revenue by the end of the year, and it has become one of Johnson & Johnson's brightest stars for the long-term future.

It's not alone in this company's oncology portfolio. Fellow oncology treatment Velcade, used to treat multiple myeloma and mantle cell lymphoma, grew sales by more than 9% through the first half of the year. That's significantly smaller growth, but like Zytiga, Velcade's on pace to exceed more than $1 billion in sales through 2013. Velcade and Zytiga both rank among Johnson & Johnson's top five best-selling drugs overall.

Pfizer's strength in oncology is still warming up, but if it can match Johnson & Johnson's fortitude in this area. it'll be a great addition to the company's well-established pharmaceutical portfolio.

Fool contributor Dan Carroll has no position in any stocks mentioned. The Motley Fool recommends Johnson & Johnson. The Motley Fool owns shares of Johnson & Johnson. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.