(Reuters) - Express Scripts, the largest U.S. pharmacy benefit manager, on Tuesday said cost savings on expensive cancer treatments could be achieved if the company were involved earlier in the decision-making process.

Express Scripts, which has become more aggressive in negotiating discounts on drugs for insurance plans and employers, in December stopped covering Gilead Sciences Inc's hepatitis C treatment after lining up a cheaper price for AbbVie Inc's newly-approved alternative.

Gilead's Sovaldi has been shown to cure hepatitis C in most patients for the first time but the pill costs $1,000 a day, which Express Scripts deemed unaffordable.

The move reignited investor concerns that pharmaceutical companies will have to bow to pricing pressure from U.S. insurers and lawmakers over novel medications whose cost can reach hundreds of thousands of dollars for some diseases.

For cancer patients, decisions on the course of treatment typically go through health insurance plans first, and medicines are not changed once people are far into their regimens, Express Scripts Chief Executive George Paz said at the J.P. Morgan Healthcare conference in San Francisco. He said pharmacy benefit managers should be included in the decision-making process at a much earlier stage.

"The big opportunity out there is really in cancer," Paz said. "If we can get out in front of that, that is a huge opportunity."

Paz said he is also focused on a new crop of cholesterol-lowering drugs that are coming to market and is talking to companies about market share, positioning and pricing.

"They are pretty astonishing, but they are also very expensive," Paz said of the drugs which target a protein known as PCSK9. Manufacturers include Amgen Inc and Regeneron Pharmaceuticals Inc. The key is to determine which are real breakthrough treatments and which are "me too" drugs, Paz said.