Boston Scientific Corp., a medical device company with major operations in the Twin Cities, closed on a $4.3 billion acquisition of British health care company BTG PLC with the goal of building a wider array of devices to detect and treat cancer in less-invasive ways.

Monday's all-cash acquisition of BTG PLC represents Boston Scientific's second-largest acquisition ever, after its $26 billion purchase of Guidant in 2006. Much smaller in scale, the BTG acquisition fits with Boston Scientific's pattern in recent years of making discrete investments for companies that make products it can sell worldwide, particularly in therapies where it already has a presence.

BTG sells several different forms of minimally invasive cancer treatments for liver and kidney cancers, which Boston Scientific chief executive Mike Mahoney has said is "the gem that has the most appeal to Boston Scientific." Those include small pellets that emit radiation or chemotherapy drugs implanted directly inside tumors via minimally invasive tools that Boston Scientific already sells.

"In interventional oncology ... we are the category leader for the delivery and access tools, and BTG is the category leader for the therapeutics. By bringing these portfolios together, we now have the deepest and broadest portfolio for our customers so that they can treat more patients," Jeff Mirviss, president of Boston Scientific's Minnesota-based peripheral interventions business, said Monday. The deal will also accelerate organic sales because the Boston Scientific peripheral business is in significantly more countries around the world than BTG, he said.

For Boston Scientific, the acquisition is expected to add between 4 cents and 5 cents of adjusted earnings per share in 2020. The company expects to add jobs in Minnesota through the deal, and is planning an expansion of its Maple Grove offices to accommodate the growth.

Mahoney told investors in January that Boston Scientific analyzed BTG's business in depth for close to a year before reaching an acquisition agreement. The deal, publicly announced in November, called for Boston Scientific to pay BTG shareholders a 36.6% premium over BTG's previous closing price, Reuters reported at the time. (The actual deal value was slightly higher than the original $4.2 billion estimate because of the final share count and foreign-exchange rates.)

The deal came under close regulatory scrutiny. Regulators eventually required Boston Scientific to agree to sell off a small cancer business that it had acquired in 2015 as a condition of buying BTG, to avoid having a combined BTG-Boston Scientific dominate too much of the overall market for interventional oncology.

On Monday, Boston Scientific formally acquired BTG, removing the company from the London Stock Exchange, while Palo Alto, Calif.-based Varian Medical Systems revealed that it intends to buy Boston Scientific's Embozene and Oncozene product lines for $90 million. Varian sells a range of diagnostic and therapeutic treatments for cancer, including the ProBeam proton-beam therapy system.

Boston Scientific has long sold a wide portfolio of medical devices used in the blood vessels, from stents and balloons to open clogged vessels to long, skinny tools that deliver medical devices and therapies to areas of the body far removed from the small incision sites.

Mahoney said the company is deliberately building a concentration of oncology devices and cancer expertise, including a $400 million deal to acquire Maple Grove's NxThera and its BPH treatment system Rezum, a $600 million acquisition of Augmenix and its SpaceOAR system for patients undergoing radiation treatment for prostate cancer, and $275 million to buy nVision Medical Corp. and its Mako 7 device for early detection of ovarian cancer. Those deals all closed last year, though the listed prices include future milestone payments.

"Recently you've seen a string of acquisitions in a focus from Boston Scientific on cancer," Mahoney told investors in January. The BTG deal, still under regulatory review at the time, "continues to expand this trend of cancer for Boston, whether it be Augmenix, whether it be nVision, the work we're doing in endoluminal surgery, and now with BTG."

Mahoney said BTG's interventional medicine business will generate more than $400 million in sales in 2019, with most of that coming from U.S. sales. BTG also sells a group of vascular devices used in the treatment of deep-vein thrombosis, pulmonary embolisms, and superficial venous disease, which will be managed from offices in the Twin Cities.

Finally, BTG has a business line comprising royalty payments related to the prostate cancer drug Zytiga. On Monday, Boston Scientific announced that it plans to divest that business by the end of the year, but further details were not available.