McKesson (MCK -2.06%) defied the bear market last year. The healthcare stock climbed in the double digits as the three benchmark indexes sank.

But McKesson's winning streak wasn't just a short-term event. The stock has steadily gained over time. That's thanks to increasing revenue and dividend growth.

You would be a winner today if you'd invested in McKesson at any point in the company's history. The stock is trading slightly lower than its peak, reached late last year. But let's take a look at how much you would have today if you'd invested $5,000 in McKesson in 2020 -- and see if more gains could be on the horizon.

A value that's doubled

If you had invested $5,000 in McKesson at the start of January 2020, you would have bought 36 shares. Today, at a price of about $338, the value of your holding would have more than doubled, reaching $12,168. At its very highest, back in November, your investment would have been worth more than $14,000.

So, whether you sold and locked in profits in November or still own the stock now, your investment has been a winning one. Now the question is: Moving forward, is there still potential for gains?

According to Wall Street, there is. The average share price forecast predicts a 26% increase in the coming 12 months.

Still, that's pretty short term. What about further down the road? Well, McKesson has reached an important transition point -- and one that should drive a whole new phase of growth. The distributor of drugs, medical supplies, and services is exiting its European businesses. In fact, the company managed to divest 11 of the 12 businesses within just a couple of years.

At the same time, McKesson is shifting its focus to higher-growth areas, specifically oncology and biopharma services. Oncology represents a $50 billion opportunity, the company says.

McKesson already has many oncology offerings in place. For instance, McKesson launched Ontada in late 2020. The platform offers technology solutions that help oncology practices manage patient data and make the best treatment decisions.

And last year, McKesson and HCA Healthcare's Sarah Cannon Research Institute formed a joint venture to improve access to clinical trials for doctors and their patients.

A strong portfolio

In the area of pharma services, McKesson also has built a strong portfolio through acquisitions. Most recently, the company said it would buy Rx Savings Solutions. The business helps employers and health plans find the best value on prescription drugs.

McKesson's gains in the oncology and biopharma services market could progressively lead the shares higher from today's level.

The company has demonstrated its ability to benefit from its investments. Return on invested capital generally has climbed over time -- and is on the rise today.

MCK Return on Invested Capital Chart

MCK Return on Invested Capital data by YCharts

It's also worth owning McKesson for two other reasons. First, the company considers rewarding shareholders one of its top priorities. In the most recent earnings call, chief financial officer Britt Vitalone said, "We will continue to return capital to shareholders through a combination of our growing dividend and share repurchases." 

Second, McKesson's general business model offers investors the safety of a healthcare company -- without one of the biggest risks. Here, I'm talking about the potential failure of drug candidates. Since McKesson doesn't develop medicines, this doesn't represent a risk for the company.

Today, McKesson shares trade for about 13 times forward earnings estimates, higher than less than 10 in recent years. Still, this looks pretty reasonable considering McKesson's track record, growth prospects, and dividend payments.

And that's why, even if McKesson shares take a pause, I wouldn't worry. This stock still could boost your portfolio in a big way over the long haul.