With expected growth at existing schools and a collection of new ones likely on the way, the country’s first-year medical school enrollment is projected to grow 21 percent over a 10-year period ending in 2012, according to a survey released by the Association of American Medical Colleges.

That would mean a collective incoming class of 19,900 students four years from now. By comparison, the survey counted 16,448 first-year students in 2002-3, its baseline year.

Two years ago, concerned about a future physician shortage, the AAMC recommended a 30 percent increase in first-year U.S. medical school enrollment from 2002 to 2015. The report notes that projecting the enrollment data out beyond 2012 using average forecasted increases for existing schools and proposed enrollment figures for the proposed schools, the targeted 30 percent growth would be reached by 2017.

"We're encouraged by the expected growth in medical school enrollment," said Edward Salsberg, director of the association's Center for Workforce Studies, which conducted the survey. "It's clearly a significant change from earlier decades, when there was no growth."

The survey relied primarily on self-reported data provided by 115 M.D.-granting U.S. medical institutions in fall 2007. More than 86 percent of existing schools that participated in the annual survey said they have already expanded the number of first-year students or plan to do so within the next five years.

According to the survey, first-year enrollment in these schools would increase by 2,635 students, or 16 percent, by 2012. This growth would push the average class size at existing medical schools from 132 students in 2002 to 152 students by 2012.

Public institutions are projected to supply 1,821 of these new enrollment slots, while 814 are expected to come from private colleges.

Additionally, at least nine institutions have taken the first step toward medical school accreditation, with some already under development, according to the Liaison Committee on Medical Education, which accredits medical education programs leading to a M.D. degree. Few new schools have emerged in recent decades.

Based on future enrollment figures, the AAMC estimates that nearly 800 first-year students would attend these new programs in 2012-3.

Planned increase in first-year enrollment by institution type and region (existing schools only)

Source: Association of American Medical Colleges

Of the existing campuses, far more said they planned to expand, or already have, at their main campus, rather than adding a new regional or branch campus. According to the report, the vast majority of respondents said they planned to target minority groups who are “currently underrepresented in medicine,” and focus on programs that provide primary care services for rural and urban underserved communities.

When asked about barriers to expansion, those surveyed listed common growth concerns, such as capacity of existing clinical sites to train more students, ability to add science and clinical faculty, and ability to fund the programs.

According to the survey, nearly half of the campuses have already built new teaching space or reconfigured existing space to accommodate the growth. Roughly 40 have added new clinical training sites, and 27 schools say they’ve hired new faculty as a direct result of their expansion plans.

Salsberg said that because medical school applications have risen over the last several years, he hasn't heard concerns from institutions about having an adequate pool of candidates to fill the new slots.

Randolph Canterbury, senior associate dean for education at the University of Virginia's School of Medicine, said his concerns have more to do with classroom and lab space, as well as having adequate clinical educators across all disciplines.

"Increasing the class by one is trivial in the lecture hall or even in a small group learning situation, but that person has to have the clinical experience as well, and that involves one-on-one training," he said.

Virginia several years ago increased its class size from 139 to 142 students but hasn't changed that number in recent years. Canterbury said school officials decided that as of now they don't have the classroom size or lab facilities necessary to support further growth. A new building scheduled for completion in 2010 could accommodate 18 more students, and Canterbury said officials will look at growing slowly once it opens.

He said that while each school has to do its own growth analysis, "it's clear that the physician shortage will get much worse before it gets better."

Patrick Duff, associate dean of students at the University of Florida's College of Medicine, says the national growth is "extremely positive" for the field.

Like Virginia, Florida in recent years increased first-year class size from 115 to 130 students. For now, Duff said, that's the ceiling. He cited classroom and lab space -- but not dearth of clinical faculty -- as the primary reasons for maintaining the current enrollment. Florida is awaiting approval of a new building that could allow that number to grow.