The Dow Jones Industrial Index is eclipsing 20,000, and while that's just a number, media coverage may have you wondering, "Is there still room to climb?" No one knows if the market will increase or decrease in the short term, but these three top healthcare stocks are disrupting their respective industries. That suggests long-term investors ought to consider owning them, regardless of the Dow.

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Reshaping surgery

Intuitive Surgical (ISRG 0.15%) pioneered the robotic surgery market, and today, its robotic surgery systems are being used daily to perform thousands of different procedures. Management just reported fourth-quarter and full-year 2016 results, and those results show that demand for robotic systems, and the instruments they require, continues to climb. Sales in the quarter improved 11.9%, to $756.9 million, while earnings per share increased 3.4%, to $6.09.

The company shipped 163 of its da Vinci robotic surgery systems last quarter, up 3.2% from Q4 2015. Fifteen percent year-over-year growth in the number of procedures performed using these devices resulted in instrument sales jumping 18.6%, to $386.3 million.

Most of the procedures that are being performed on da Vinci systems currently are urology and gynecology procedures, but the company thinks that it can steadily increase the use of da Vinci across other procedures, too. In 2015, there were 652,000 procedures done worldwide on these systems -- however, management pegs its addressable patient population at 4 million procedures.

If the company continues to convince surgeons that da Vinci is safer and more effective than typical surgery, there could still be a lot of upside ahead. Management's got a bullet-proof balance sheet that includes $4.8 billion in cash, equivalents, and investments -- and no debt -- so it has plenty of financial flexibility to invest in innovation and training to expand da Vinci's procedure market share. 

Accelerating gene research

Drug research is laser focused on creating next-generation drugs that target specific genetic mutations, particularly in cancer. That bodes well for Illumina Inc. (ILMN -1.62%)

With more than 7,500 systems installed worldwide, Illumina is the global leader in gene sequencing. And this year, Illumina plans to launch two new sequencing systems that provide greater genetic insight at a lower cost.

The NovaSeq 5000 and NovaSeq 6000 allow researchers to perform ultra-deep sequencing that can lead to a significantly greater understanding of the relationship between genes and disease. Over time, management says these machines could decrease the cost of gene sequencing to as little as $100 from $1,000 or more today. If so, then gene research that has heretofore been too costly and complex to perform may become possible.

In the past, when Illumina launched new technology that lowered costs associated with gene research, it fueled significant sales and profit growth for the company. Personally, I think there's a good chance that may happen again with the launch of these new machines.

Illumina is already a growing company with $607 million in quarterly sales and $144 million in quarterly net income, yet its shares have slipped in the past year because of purchasing delays caused by the timing of research budgets. Although a forward P/E ratio of 44 means that Illumina's shares aren't cheap, I think its growth potential deserves a premium. If I'm right, then buying shares now for the long haul could be savvy.

A new era in cancer treatment approaches

Kite Pharma (NASDAQ: KITE) shares have fallen in the past year because of pushback on drug prices. However, its research into chimeric antigen receptor T-cell therapies (CAR-T) could significantly transform treatment for thousands of cancer patients. 

The company's already begun work on an application for U.S. Food and Drug Administration (FDA) approval of its first CAR-T, Axi-Cel, for use in B-cell cancers. Management thinks that application will be complete later this quarter. If so, then the FDA could weigh in with a decision on Axi-Cel before the end of this year.

If approved, Kite Pharma's prepared to produce enough Axi-Cel to initially treat 4,000 patients annually, and because cancer therapies usually launch with six-figure price tags, Axi-Cel could reach the nine-figure sales market quickly. In trials evaluating Axi-Cel in B-cell cancers, including diffuse large B-cell lymphoma, or DLBCL, the objective response rate was an impressive 79%.

Assuming the FDA doesn't find anything in Axi-Cel's safety data that derails its potential commercialization, this drug could become a standard of care that changes how oncologists treat these cancers. Given that opportunity, plus the chance to expand CAR-T to other cancer indications, this could be a high-risk, high-reward stock that makes sense for long-term growth investors to buy.