GEOFF BENNETT: The Vatican says that Pope Leo has lung cancer and that doctors removed the lower lobe of his right lung today in a surgery that lasted roughly 90 minutes.

In a statement, the Vatican called the operation successful and said there were no complications.

For more on the pope's prognosis, we're joined by Dr.

Omer Awan.

He's a radiologist and a senior public health contributor for "Forbes."

Thank you for being with us.

First, explain what particular type of lung cancer this is and how serious the diagnosis this is.

DR.

OMER AWAN, Radiologist: Sure, Geoff.

So the pope was diagnosed with adenocarcinoma.

That's the most common type of lung cancer.

It produces some substances in the lung like mucus, for example.

This cancer can be seen in both smokers and nonsmokers.

I'm somewhat optimistic about this because they did say that it was localized.

It was a localized form of lung cancer.

And that means presumably it hasn't spread to other parts of the body.

We don't know that definitively, but presumably that's what that means.

And also the size of this lesion, we know, before it was removed, it was a nodule.

By definition, a nodule is three centimeters of size or less.

A mass would be greater than three centimeters.

So those are all positive features of this lung cancer.

GEOFF BENNETT: Is removing an affected portion of the lung, is that curative, or would someone with this diagnosis typically need treatment, such as radiation or chemotherapy?

DR.

OMER AWAN: That, Geoff, will really depend on some of the features that we see on pathology, which is the report that's given once they have run tests on the tumor once they have removed it.

So, for example, were the surgical margins clear?

And what we mean by that is, is there any residual tumors still left in the lung after they have removed it?

Has it spread to other parts of the body?

That's going to be important because that would be an ominous sign.

And also the biological characteristics of the tumor, some features can increase the risk of recurrence.

So all that information really needs to be seen and understood before we can really understand the prognosis of the tumor.

And that will be given once the pathology report is seen.

GEOFF BENNETT: The pope is 71 years old.

He maintains a demanding schedule, to say the least.

What does recovery from this type of surgery typically involve?

DR.

OMER AWAN: Well, they have removed one lobe of the lung, and the right lung has three lobes.

So they removed one out of the three lobes.

So that can certainly reduce the function and capacity of the lung, but the lung does compensate and expands with time.

So initially the pope is going to deal with just walking around, eating, making sure he can go to the bathroom.

But then, with time, after a week or so, they will have to work on his lung function, breathing exercises, his stamina.

Leaving the hospital is very different than fully recovering, because he does have a very demanding schedule.

So he may leave the hospital, but he may not be fully recovered.

And that's going to take weeks, perhaps even months, depending on his underlying health and his underlying lung function and stamina, as he does more breathing exercises with his medical team.

GEOFF BENNETT: Dr.

Omer Awan, thank you for being with us.

We appreciate your insights.

DR.

OMER AWAN: My pleasure.

Thanks.