When the sun is out, many of us reach for sunscreen, but myths and misinformation have left some people confused about when and how to use it, and how to ensure we still get enough vitamin D. , a skin cancer expert at QIMR Berghofer Medical Research Institute in Australia, has led clinical trials looking at the link between sun exposure and skin cancer, and sunscreen use and vitamin D. She also recently led the development of a new that considers how to balance the risks and benefits of sun exposure. Here, she lists five things that everyone should know about sunscreen.

Sunscreen should be used as a last line of defence

Many people think it’s OK to lie on the beach all day in a tiny bikini as long as they rub sunscreen all over their exposed skin and reapply it every 2 hours. They think sunscreen makes them bulletproof. But even if you apply the best sunscreen perfectly, it still lets some ultraviolet (UV) radiation through. If you’re out in the sun for hours, that gradually adds up to a dose that is big enough to cause skin damage. At that point, it doesn’t matter if you apply more sunscreen; the damage is already done.

People often assume that if they reapply sunscreen every 2 hours, they’re sort of starting the protection again, but that’s not how it works. You also need to protect yourself with a hat, sunglasses, rash shirt or other protective clothing, and stay in the shade in the middle of the day. Sunscreen should be considered a last line of defence for the parts of your skin that you can’t easily cover while you’re outdoors, like your hands and neck.

There is good evidence that sunscreen protects against skin cancer and wrinkles

The largest, longest-running study of sunscreen was conducted in the Australian town of Nambour. In 1992, 1600 people in the town were randomised to apply daily sunscreen or continue with their normal sunscreen use, which tended to be minimal. It found that those who applied the daily sunscreen were years down the track.

The researchers also created moulds of the backs of the study participants’ hands to look at damage to the surface of the skin. Those in the daily sunscreen group had compared with those who didn’t. When they were followed up on in 2014, they also had .

The sunscreen to choose is the one you like wearing

It’s no good having sunscreen that sits in your cupboard and doesn’t end up on your skin because you don’t like the feel of it. If you’re going on a hike and you’re going to be out all day, it’s better to wear sunscreen with a high sun protection factor (SPF) of 50+. But it’s harder to get a high-SPF sunscreen that feels really nice, so if you’ll be popping out for only short periods throughout the day, you can choose an SPF 15 or 30 sunscreen. Tinted sunscreens can offer the same protection as normal sunscreens, but only if you apply them thickly. But because these often make the skin look overly tinted, people tend to apply them too thinly. One option is to first put on a thick layer of normal sunscreen, then apply the tinted sunscreen on top of it.

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Chemical sunscreens, meaning those that contain organic ingredients such as octocrylene and avobenzone, work by absorbing UV radiation from the sun and converting it to harmless heat. Inorganic sunscreens, also known as mineral or physical sunscreens, contain zinc oxide or titanium dioxide particles. They are often reported to work by reflecting or scattering UV radiation, but they actually , like chemical sunscreens.

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Wearing two layers of sunscreen helps to achieve adequate coverage

You get the SPF listed on the bottle only if you apply 2 milligrams of sunscreen per square centimetre of skin, which is around in an average adult. But it’s really hard to apply this amount of sunscreen in one go. One day, I decided to measure it out exactly, and I couldn’t rub it all on; it was too much. So now, I apply one layer, let it sink in while I brush my teeth and do other things, and then a second layer, so I can apply the full recommended amount.

I was born in Armidale, Australia, in the late 1960s and didn’t wear sunscreen as a child, despite my pale skin. I’ve since had three skin cancers removed, the first of which appeared when I was just 29. So now, I am careful to protect my skin.

If you’re diligent with sunscreen, you might need to take a vitamin D supplement

We recently conducted a trial called the Sun-D Study to see whether applying SPF 50+ sunscreen every day affects people’s vitamin D levels. We randomly assigned 639 people to apply SPF 50+ sunscreen as part of their daily morning routine on days when the UV index was forecast to reach 3 or higher, or to use it at their own discretion. After about a year, a – about 46 per cent compared with 37 per cent in the control group. If you wear sunscreen every day, I would advise taking a vitamin D supplement so that you don’t become deficient, especially in winter. I take one myself – they are cheap, safe and effective.

People with dark-coloured skin are at greater risk of developing a vitamin D deficiency. I recently led the development of a new that looked at how to balance the various risks and benefits of sun exposure. It brought together experts from many Australian universities and medical organisations, and it concluded that people with dark-coloured skin need to put on sunscreen only if they plan to spend more than 2 hours outdoors on days with high UV radiation levels. This is in recognition of the fact that melanoma incidence is 30 times lower in people with dark-coloured skin than in those with light-coloured skin, and that vitamin D deficiency poses a greater risk.

I started to wonder if something funky was going on when multiple people in my family got cancer around the same time. In 1990, my older sister Rebecca was diagnosed with acute lymphoblastic leukaemia, when she was 21 and I was 14. While she was undergoing rigorous chemo, my mum was diagnosed with breast cancer.

Rebecca passed away in 1994 and then, a couple of years after that, my dad got bowel cancer. While he was undergoing treatment, my mum got cancer in her other breast. She survived that, but then she was diagnosed with oesophageal cancer in 2009. She had major surgery, but it came back and she died six weeks later.

In 2020, my other sister was diagnosed with fast-growing triple-negative breast cancer and I thought, oh my god, there’s something going on here. My sister was tested for the BRCA mutations, variants of the BRCA1 and BRCA2 genes that increase breast cancer risk, and it came back negative.

So then she was tested for a different mutation in a gene called TP53, which is much rarer but even worse. Women with this mutation have , with a 50 per cent chance before the age of 30. It’s called Li-Fraumeni syndrome and it basically means your TP53 gene, which normally functions as a cancer-suppressing gene, is a dud.

When my sister was offered the test, I was like: “What’s Li-Fraumeni syndrome?” It’s not something you ever hear about. The test came back positive and she was extremely distraught. Since it can run in families, I was then offered the test too. I decided to do it because I didn’t want my sister to go through this journey on her own.

I had the test in 2022, when I was 47, and it came back positive. I actually felt at peace with it, which a lot of people find surprising, but it was because I finally felt like I had answers for all the troubles my family has been through. It’s a personal thing, though – my brother, for example, has chosen not to get tested.

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After getting the diagnosis, my life changed forever. When you have Li-Fraumeni syndrome, there isn’t an hour where you don’t think about it. It’s always on your mind. Within months of finding out I had the gene, I had a double mastectomy as a preventative measure. They found two ductal carcinomas in situ, early forms of cancer, in my left breast after it was removed.

I live in Sydney, so I was able to join an that is investigating annual whole-body MRI as a way to spot tumours in any location in people with mutations in TP53 or other genes that can cause cancer in multiple organs. I had my first one in 2022 and I was very nervous because I didn’t know if they’d find anything. It was normal, but in the second year, they found a 9-millimetre meningioma – a tumour in the meninges, the layers of tissue covering the brain. Fortunately, it’s benign, but I was very freaked out about it. It was a bit of a gamechanger for me.

I have my annual whole-body MRI every November and my “scanxiety” starts building from around July. I start thinking, is this going to be the year when everything changes? But being part of the study also gives me a sense of reassurance, because it’s designed to pick up cancers at an early stage when they are hopefully still treatable. My sister, who survived her breast cancer, now has annual MRIs too.

In addition to whole-body MRI, I have yearly skin checks with a dermatologist and an annual blood test. Every two years, I also have an endoscopy and colonoscopy. They’ve found polyps, abnormal cell growths that can develop into cancer, in my bowel, which were removed, plus some atypical cells in my oesophagus, which they’re keeping an eye on. I’m also on constant alert for anything unusual in my body. I’ll have a sore shoulder and get nervous because I’ll wonder, is this going to be something?

My geneticist thinks my mum might have had a de novo mutation, a mutation that arises spontaneously in an individual rather than being inherited, in her TP53 gene, which was passed down to me and my sisters. We don’t have children, so there isn’t a risk of us passing it on further.

My partner has been really supportive. After I found out I had the syndrome, he said: “You’ve just got to do what you’ve got to do.” When I had my double mastectomy, I didn’t go down the path of having a breast reconstruction and I was worried I looked like a freak, but he said: “Not at all. Your scars tell your battle.”

I try to stay positive because I figure that everyone has something they’re dealing with, be it a chronic disease or an injury or depression, and this is just my thing to bear. My sister-in-law, for example, recently had a stroke. We all have our things – some are visible and some are not – so we need to be compassionate towards each other. Life isn’t a white picket fence.

As told to Alice Klein

A daily pill doubles the survival time of people with pancreatic cancer, one of the most aggressive and difficult-to-treat forms of the condition, even after they have stopped responding to chemotherapy. What’s more, the convenient pill has fewer side effects than standard chemotherapy.

“It’s a transformative treatment,” says at University College London, who wasn’t involved in the research. “For decades, [survival outcomes] haven’t changed for pancreatic cancer. [The new treatment] gives you double the amount of time to enjoy your life, be with your family and do things that you would like to do.”

About 70 per cent of people with pancreatic cancer . A combination of no routine screening and vague symptoms, like a sore back, means that the condition is usually spotted when it has spread elsewhere. Standard treatment involves chemotherapy, but even then, most people only survive for about , on average. “The disease is really aggressive and difficult to treat,” says Acedo.

More than 90 per cent of pancreatic cancers are driven by mutations in the KRAS gene, which encodes for a protein known as K-Ras. When the gene is mutated, K-Ras gets stuck in a state that drives cancer cells to divide uncontrollably.

at Memorial Sloan Kettering Cancer Center in New York and her colleagues wondered if a drug called daraxonrasib, which binds to the protein, could dampen its signals and slow the growth of cancer cells.

So the team recruited 500 people with metastatic pancreatic cancer from the US, Europe and Asia, all of whom had stopped responding to an initial round of chemotherapy. They were assigned to two groups: the first took daraxonrasib every day and the second continued to receive standard chemotherapy infusions.

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The researchers – who presented at the American Society of Clinical Oncology meeting in Chicago on 31 May – found that the participants in the daraxonrasib group went on to survive for 13.2 months, on average, compared with 6.7 months in the chemotherapy group. “It’s fantastic news,” says Acedo. The treatment is the first in decades to improve survival outcomes among patients with advanced pancreatic cancer, she says.

What’s more, only 1 per cent of the participants in the daraxonrasib group stopped taking the drug due to side effects, such as rash, whereas 11 per cent stopped chemotherapy due to adverse events like fatigue. “A daily pill is also much easier to take than chemotherapy, which involves frequent hospital visits and is invasive,” says Acedo.

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The team has submitted the findings to the US Food and Drug Administration, and hopes to get the drug approved for use in people with metastatic pancreatic cancer who have had chemotherapy in the coming months, says O’Reilly.

But it is still far from a cure, says Acedo. “It’s a few extra months, which is really promising, but it’s still not years and they’re still dying of the disease,” says Acedo. Nevertheless, further studies may reveal that combining daraxonrasib with other experimental drugs or chemotherapy could lead to even better outcomes, she says.

The researchers are exploring this in ongoing trials, says O’Reilly. They are also looking at whether daraxonrasib could be used as a first-line therapy in untreated patients, she says.