A $1.5 million gift to Roswell Park Cancer Institute from New Era Cap Co. will allow construction to start next year on a major addition to the cancer center.

The gift announced Thursday brought to $40 million the amount raised for the 11-story Clinical Sciences Center planned for the northwest corner of Michigan Avenue and Carlton Street, abutting the cancer center’s main hospital building.

“New Era’s donation is the gift that will make the building possible. It’s a go now,” said Leslie Garrity, a Roswell Park spokeswoman.

The project adds to the growing list of ongoing or planned construction at the downtown Buffalo Niagara Medical Campus.

Construction also will start next spring on a new $200 million children’s hospital a short distance away at the corner of Ellicott and High streets.

Recent projects in the five-block area that comprises the Medical Campus include the Gates Vascular Institute, the University at Buffalo’s Clinical and Translational Research Center and Kaleida Health’s new nursing home, HighPointe on Michigan.

In addition, UB is building a new Educational Opportunity Center, which will connect with UB’s Downtown Gateway building, formerly known as the M. Wile building. A large portion of the former Trico building has been transformed into incubator space for fledgling high-tech companies.

As significant as those projects have been to the growth of the campus, they may soon be overshadowed in size, cost and scope.

UB last year announced a huge initiative to relocate its School of Medicine and Biomedical Sciences from the South Campus on Main Street to the Medical Campus. Officials have talked about starting the project next fall and completing it in 2016, at a cost estimated about $375 million.

Services in Roswell Park’s Clinical Sciences Center will include a breast care center, an expanded chemotherapy infusion clinic, a clinic for adolescents and young adults, patient education programs and office space for physicians and researchers.

The current hospital building was completed in 1998 as part of a $241 million project to reconstruct the cancer center campus. The new facility, which will connect to the hospital building, reflects growth in patient business at Roswell Park, officials said.

“Over the past five years, we have seen a nearly 40 percent increase in patients, and we have seen an almost 60 percent rise in outpatient appointments over the past decade,” Dr. Donald L. Trump, chief executive officer, said.

Relocation of some services to the new Clinical Sciences Center also will allow for renovation and expansion of other services in the main building, officials said.

The 11-story Roswell Park expansion project previously received a pledge of $10 million from 10 local philanthropists and their families dubbed the “Circle of 10” by the fundraising Roswell Park Alliance Foundation, $10 million from the Roswell Park Cancer Institute Corp. and donations from other contributors. In total, 435 donors contributed to a campaign to raise money for the new building, cancer center officials said.

New Era, which is headquartered in Buffalo, has been the exclusive provider of caps for Major League Baseball and its minor league affiliates since 1993 and is also the official on-field cap supplier for the National Football League. The company has been a supporter of cancer research and education for the past decade.

“At New Era, we strongly believe in giving back to the communities that we work and live in. One important way we do this is by engaging in partnerships and signature programs that focus on finding a cure for cancer,” Christopher Koch, chief executive officer, said.

Koch’s father, David, who formerly headed New Era, died in 2002 of cancer.

The Circle of 10 includes West Herr Ford President Scott R. Bieler; National Property Management Associates founder William T. Gacioch, his wife, Nancy, and family; the Garman family and its foundation; former Gioia Macaroni owner Richard Gioia and his wife, Anne, as well as Anthony and Donna Gioia; executive and community leader G. Wayne Hawk and his wife, Charline; the Jacobs family, owners of Delaware North; Patrick P. Lee, director of the Patrick P. Lee Foundation; Buffalo News Publisher Stanford Lipsey and his wife, Judith; the family of the late poet and Canisius College economics professor Lawrence Minet; and Buffalo Bills owner Ralph Wilson Jr.

The project is envisioned in two phases. The $40 million is enough to open floors one through seven by 2015. Plans are to raise an additional $10 million to build out the remaining floors, Garrity said. The building was designed by FxFOWLE Architects of New York City.

Recently Roswell Park announced that the cancer center will consolidate its services for young patients with cancer and blood diseases with services offered by Kaleida Health on a floor of the renamed John R. Oishei Children’s Hospital, a replacement for the Women & Children’s Hospital campus on Bryant Street.

The new pediatric hospital will go up across from and be connected by a walkway to Buffalo General Medical Center. Completion is scheduled for early 2016.

The Medical Campus includes the Hauptman-Woodward Institute, which is housed in a notable new building, d and UB’s Center for Excellence in Bioinformatics & Life Sciences, which opened in 2006 and is connected to Roswell Park Cancer Institute’s genetics and pharmacology building. 2006.