TRENTON, N.J. – Pfizer Inc. is shifting its research focus to diseases that have high potential for treatment improvements, such as cancer and Alzheimer's disease, and where it can be a market leader.

The world's biggest drugmaker also is ending new research in heart disease, including treatments for high cholesterol and hardening of the arteries, as part of a standard, periodic tweaking of its research strategy, spokeswoman Liz Power said Tuesday.

Pfizer expects to spend between $7.2 billion and $7.5 billion on research and development this year, a huge budget for the industry.

Like most of its competitors, Pfizer has been reorganizing and cutting costs to deal with looming generic competition and a lack of blockbusters in its pipeline.

Power said Pfizer needs to focus research, particularly costly late-stage human testing, on areas where patient needs aren't meant by existing treatments, where there's a sizable commercial market and where the company has expertise and a good chance for scientific success.

The New York-based company has identified six high-priority areas for research: cancer, pain, inflammation, diabetes, Alzheimer's disease and schizophrenia.

Heart drugs remain a huge market given the aging population in developed countries, and Pfizer sells the world's top-selling cholesterol fighter, Lipitor. However, that market is considered saturated, and many drug categories already have significant generic competition that is eroding sales of brand-name medicines.

Lipitor, which generates about $12 billion a year in revenue, will lose its U.S. patent late in 2011. The experimental drug considered Pfizer's most promising candidate as a successor, torcetrapib, was yanked from development late in 2006 because it was linked to an unexpected number of deaths and heart complications.

Meanwhile, Pfizer on Tuesday gave its semiannual update for investors on its research pipeline, stating that it now has 114 human studies of drugs in process and that the number of studies in the final stage has grown from 16 to 25 since its last update in March. Biotechnology drugs, which generally are extremely profitable, will be a big part of that pipeline, particularly in cancer research.

In morning trading, Pfizer shares were up 15 cents to $17.80, near their 52-week low and at about the same level where they traded in the summer of 1997.