Cancer specialist US Oncology will be bought by McKesson, a leading US drug distributor, in a stock-and-debt deal worth about 2.16 billion dollars, the companies said.
McKesson will buy all outstanding shares of US Oncology for cash and assume its debt.
"The combined organization will focus on providing a comprehensive offering of solutions for the oncology industry, one of the fastest-growing segments in healthcare," they said.
The transaction, which requires regulatory approval, was expected to close by December 31.
McKesson chairman and chief executive John Hammergren said the tie-up with the community-based cancer treatment and research firm would offer a "compelling suite of services and solutions to community oncologists and other partners in the rapidly evolving specialty business."
The combined McKesson specialty care business will have 3,000 physician clients and be led by Bruce Broussard, chairman and CEO of US Oncology.
Shares in San Francisco-based McKesson rose 17.0 percent to 67.10 dollars in late morning trade in New York.