Bipolar treatments, babies born before arrival, calcium, vitamin D and polyps and the different types of diabetes

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Health Report 28 min 4 speakers 5 chapters transcribed 1 hour ago

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What is the main topic discussed in this episode?

Dr. Norman Swan 0:00

Hello and welcome to the Health Report with me, Norman Swan. Today, born-before-arrival babies. What is it about babies who are born before the mum can get to the labour ward?

What are the risks and outcomes for babies born before reaching the hospital?

Dr. Norman Swan 0:10

And how well do they fare? The best treatment for bipolar disorder – the oldest and cheapest might be the one – How type 2 diabetes might actually be five different conditions, each of which needs its own treatment. And bowel cancer, one of the commonest internal malignancies and causes of cancer death. It's preventable through the detection of polyps in the bowel before they turn cancerous. There's been evidence that people on a diet that's naturally high in vitamin D and calcium protects against bowel cancer. But a recently published trial of vitamin D and calcium supplements has made a worrying discovery in relation to a type of precancerous polyp called a serrated polyp. Seth Crockett was the lead author.

Dr. Norman Swan 0:49

He's at the University of North Carolina, and I spoke to him earlier.

Seth Crockett 0:52

My pleasure. Thank you for having me.

Dr. Norman Swan 0:53

How important are these serrated polyps in general?

Seth Crockett 0:57

These are really interesting type of colon polyps. Serrated polyps are sort of like the less common cousin of the more typical precancerous polyp that we pick up on colonoscopy known as adenomatous polyps. They are really difficult to find on colonoscopy and other screening tests. and they differ from adenomatous polyps in terms of the steps they take to develop into a cancer.

Dr. Norman Swan 1:23

Is a serrated polyp more likely to turn into cancer faster than an adenomatous polyp?

Seth Crockett 1:27

an active area of research. At this point we think that their risk of cancer is about the same as an adenomatous polyp, but there are certain types of serrated polyps that we think have the potential for more rapid growth and transformation into

Dr. Norman Swan 1:42

colon cancer. I don't know if we know the answer to this question, but if you take all colorectal cancer, all cancer in the large bowel, what proportion would come from adenomatous polyps versus serrated polyps?

Seth Crockett 1:52

So we think about 20 to 30% of colorectal cancer, this is sporadic colorectal cancer, so occurring in patients who don't have a familial syndrome or genetic predisposition. So about 30% of those cancers are due to a serrated polyp precursor.

Dr. Norman Swan 2:12

Now you started this randomized trial in the belief that calcium and vitamin D would actually reduce the incidence of polyps.

Seth Crockett 2:18

We did. The study was undertaken and it was a pretty large effort, 11 centers across the U.S., over 2,000 participants who had had a colonoscopy and a polyp detected at baseline and they were randomized to receive calcium, vitamin D, the combination of those two or placebo.

Dr. Norman Swan 2:38

And this was really a chemoprevention trial where you were seeing whether you could prevent the incidence of further polyps?

Seth Crockett 2:42

Exactly, yes. As you pointed out, the study was undertaken because A number of studies have shown that patients with diets rich in calcium and vitamin D appear to be at lower risk of developing polyps and even colorectal cancer. So the idea was maybe if we give them more, that that would have a preventive effect or protective effect against colorectal cancer.

Dr. Norman Swan 3:06

So you did this randomization. You followed them up for several years. What did you find?

Seth Crockett 3:10

Looking at that more common polyp type, adenominous polyps, there essentially was no benefit at all of either calcium, vitamin D, or the combination. So that was somewhat surprising. We undertook the subsequent study to look at this other type of polyp. Contrary to our expectations, more than doubling of risk for serrated polyps six to ten years after the initiation of this study.

Dr. Norman Swan 3:36

And did you find any cancers?

Seth Crockett 3:38

Our report does not look at cancer as an outcome. We use the precursor lesions or the precancerous polyps as sort of a surrogate for cancer, and it helps us understand things that may protect against cancer. Polyps, we think, would also protect against cancer and vice versa.

Dr. Norman Swan 3:56

So why should, if a diet rich in calcium and vitamin D seems to be protective, and that's often a diet that's rich in vegetables, that's a surrogate. There's been plenty of studies suggesting that a vegetable-rich diet that's low in red meat is protective against colorectal cancer.