The U.S. Food and Drug Administration isn’t exactly known for acting fast, but that may be changing. Using an accelerated approval process, the FDA on Tuesday greenlighted a new breast cancer drug from Pfizer PFE —more than two months earlier than the company expected a decision.

The medication, known as Ibrance, has been at the head of Pfizer’s pipeline, and represents a big opportunity for the pharmaceutical firm, which has been struggling to replace lost revenue from former blockbusters like Lipitor whose patents have recently expired.

Designed to treat advanced stages of the most common type of breast cancer in postmenopausal women, the drug could be Pfizer’s next major moneymaker, with Wall Street analysts predicting it will bring in as much as $4 billion in 2020. J.P.Morgan, for one, forecasts that Ibrance will rake in $350 million in sales this year, and surpass $1 billion as soon as next year.

And if the FDA keeps up its early-bird pace of new drug approvals, more pharmaceutical companies could be in for pleasant surprises as well. In December, for example, the agency approved Bristol-Myers Squibb’s BMY new melanoma drug Opdivo more than three months ahead of schedule, as well as Amgen’s AMGN leukemia drug Blincyto more than five months early.

In each case, the FDA considered the drugs “breakthrough therapies,” and granted them priority review, an expedited evaluation process in which the FDA aims to issue a decision within six months after a new drug application is officially accepted.

The FDA approved 41 novel drugs in 2014—the highest in almost two decades, according to the FDA. Of those new drugs, 61% were given priority review status, and 20% received accelerated approval.

To some experts, the surge in drug approvals indicates a friendlier regulatory environment for pharma firms.

“Some things were getting approved on first try,” says Joe Rosenberg, a senior analyst at Nasdaq specializing in healthcare, noting that the FDA has not been asking for additional review proceedings as often as in the past. “That’s a big thing for these companies.”

An FDA spokesperson says the agency generally weighs the need for extra review processes (such as an advisory committee or panel) against the “significant resource commitments” they would entail, and believes such steps “should be used for important matters.”

Faster approval for promising medications, especially those for terminal diseases where few successful treatments exist, can also benefit patients, says Len Lichtenfeld, deputy chief medical officer for the American Cancer Society. “Most of us in the oncology community feel that the FDA, and its oncology group in particular, have been responsive to understanding the needs of cancer patients and moving drugs through the process as quickly as possible, particularly when they meet unmet needs and show significant improvement,” Lichtenfeld says.

Pfizer CEO Ian Read, for his part, hailed the approval of Ibrance as the “first new medicine” approved in more than a decade for women with a hormone-sensitive type of breast cancer (positive for estrogen receptors and negative for human epidermal growth factor receptor 2). That form of the disease makes up the majority of breast cancer diagnoses, according to Lichtenfeld.

Until now, those patients were typically just treated with letrozole, a hormone therapy originally marketed by Novartis NVS as Femara, which was initially approved for some types of breast cancer in 1997. Pfizer’s Ibrance is meant to be prescribed in combination with its predecessor treatment.

In clinical trials, Ibrance nearly doubled the time patients survived, without their disease worsening, to more than 20 months, up from the roughly 10-month prognosis for those taking letrozole alone.

“For someone, it may buy considerable amounts of time. It’s never enough, but it is important,” Lichtenfeld says. That type of advanced breast cancer is not considered a curable disease, he adds, “so any advance that is made in the treatment of those women is significant.”

Last year, nearly 233,000 women were diagnosed with breast cancer in the U.S., and an estimated 40,000 died from the disease, according to the National Cancer Institute.

“It’s exciting to think about the potential of this new medicine to help so many patients with advanced disease,” Pfizer chief medical officer Mace Rothenberg said in a statement.

Still, Lichtenfeld cautioned that it’s important to continue monitoring the effects and impact of new drugs—especially those approved quickly. For example, in 2011, the FDA revoked its approval of Genentech’s Avastin for breast cancer—nearly four years after approving it on an accelerated basis.