New findings on cancer survival rates offer hope for the more than 2 million Americans diagnosed each year. Seven out of 10 Americans diagnosed with cancer now survive five years or more, according to the American Cancer Society, a 7 percent increase since the mid-1990s, when the rate stood at 63 percent.

The survival rate data — from patients diagnosed with cancer between 2015 and 2021 — showed, significantly, that those with high-mortality cancers and advanced diagnoses had the largest gains. Myeloma survival rates, for example, rose from 32 percent to 62 percent, and liver cancer survival rates from 7 percent to 22 percent.

In an interview edited for clarity and length, Harold J. Burstein —an oncologist at Dana-Farber Cancer Institute and professor at Harvard Medical School — weighed in on the findings.

What are some of the most noteworthy changes in the cancer treatment landscape over the last few decades that have led to these improvements?

These numbers reflect medical progress as well as public health measures and changes in society at large.

If you look at the data, you’ll see that there has been a steady decrease in the incidence of lung cancer. That’s because Americans are smoking less, and so that’s a social trend that has had huge payoffs in terms of reduced incidence of lung cancer. Another major trend is that the incidence of colorectal cancer has been steadily declining. That’s because there was much more early detection of precancerous lesions, like colon polyps that are found on colonoscopy. There has been a steady decline in cervical cancer because of pap smears. There’s other early detection like breast cancer screening mammography, where it’s not that the number of cases has declined, but the stage has been downshifted so that women have a better prognosis.

Then there’s been improvement in treatment. We’ve had some good steps forward in multiple diseases, particularly in the curative setting. What we’re seeing in recent years is how immunotherapy is curing certain types of lung and breast and bladder cancer and melanoma in a way that it hadn’t before. We didn’t have tools to do that before. We are seeing steady progress in treatment of certain kinds of leukemia like chronic myelogenous leukemia and chronic lymphocytic leukemia, where the drugs get better and better and keep the cancer at bay for longer and longer.

We are seeing real improvement in metastatic disease treatment as well. So ultimately, the life-threatening part about cancer is usually metastatic disease when it spreads to other parts of the body. We’ve seen all these targeted drugs emerge where patients with advanced lung cancer can live longer. We’ve seen immunotherapy approaches in multiple different cancer types, including skin cancers like melanoma and renal cell carcinoma and multiple myeloma. Now, patients are living years and years and years longer, with dozens of new drugs helping promote their survival in the advanced stage setting.

“We are finding treatments that are both more effective and less toxic than previously. We’re seeing patients living longer, but they’re also able to enjoy life more.”

What are you seeing in the field that isn’t showing up in the data?

What’s not captured in this data is that we’re often curing as many people, if not more, while doing less of certain things: less surgery for breast cancer, less surgery to the armpit, less surgery in head and neck cancers, because the drugs are better and we can use radiation therapy without doing laryngectomies, where people lose their voice.

We are finding treatments that are both more effective and less toxic than previously. We’re seeing patients living longer, but they’re also able to enjoy life more. For many people, even though they are living with metastatic disease, the improvements in their survival are important. They’re able to lead very full and rich lives while being treated for advanced cancer.

One treatment option includes new molecular discoveries, where we’re able to tailor the treatment based on the science. For example, CAR-T-cell therapies. These are very interesting, complicated bioengineered cells that attack many kinds of lymphoma. These have been used in mostly refractory lymphoma cases, diseases that used to be unmanageable.

I think that people in the lung cancer space would say they have seen transformational experiences — not just that people quit smoking, but they’ve developed a whole toolbox of targeted therapies for patients who do have early-stage lung cancer or late-stage lung cancer, which now define the molecular targets and allow us to go after those with real rigor.

In my space, which is breast cancer, we’re able to use less chemotherapy for many patients with the most common types of breast cancer, because we now have a test which allows us to figure out who needs chemo and who doesn’t. So that doesn’t show up in these statistics, but from a patient point of view, those things are all critically important.

Are there cancers where outcomes have not improved?

It’s been widely reported that there’s been an uptick in early-onset colorectal cancer in people under age 50, and we don’t really understand why that is. There are also some tumors that remain very challenging, such as pancreas cancer, where there’s been far too little improvement in outcomes. It’s a disease where we do not have good early detection strategies, and we do not have good treatments once the cancer is identified.

Another would be glioblastoma, a brain tumor, where we haven’t made the progress I think anyone would have wanted or hoped for going back over the past 20 years. But there are many cancers — prostate cancer, breast cancer, colorectal cancer, skin cancers, certain kinds of leukemia and lymphoma — where we very comfortably look people in the eye and say, “You have an excellent prognosis with treatment, and the vast majority of people with your kind of cancer are going to be cured.” And there are other patients who have advanced cancers, where we are now able to look them in the eye and say, “You have an incurable disease, but a very treatable disease. A disease that we can use highly effective, not-so-awful drugs to hopefully control the cancer for a long period of time and allow you to lead a very happy and successful life for a long time yet.”

What this data underscores is that it’s really important to get treatment. It’s really important to have early detection. It’s really important to prevent cancer when we can.

A fraction of cancers, usually said to be 5 percent to 10 percent, have some kind of hereditary component. One of the other tools that we now have is genetic testing. For a lot of patients, what happens is that one family member is diagnosed and is found to have a genetic mutation that predisposes them to cancer, and then other family members can be tested. That can often be very empowering, both to accelerate our screening programs for them, or when available to do prophylactic surgery so that they never develop cancer. That kind of very individualized genetic information, again, is another small piece of this bigger puzzle, but it allows families to often prevent or diagnose very early a cancer that in previous generations would have been devastating.