Receiving a cancer diagnosis is life-changing and can cause a range of concerns about ongoing health.

Fear of cancer returning is one of the top health concerns. And managing this fear is an important part of cancer treatment.

But how likely is it to get cancer for a second time?

Why can cancer return?

While initial cancer treatment may seem successful, sometimes a few cancer cells remain dormant. Over time, these cancer cells can grow again and may start to cause symptoms.

This is known as cancer recurrence: when a cancer returns after a period of remission. This period could be days, months or even years. The new cancer is the same type as the original cancer, but can sometimes grow in a new location through a process called metastasis.

Actor Hugh Jackman has gone public about his multiple diagnoses of basal cell carcinoma (a type of skin cancer) over the past decade.

The exact reason why cancer returns differs depending on the cancer type and the treatment received. Research is ongoing to identify genes associated with cancers returning. This may eventually allow doctors to tailor treatments for high-risk people.

What are the chances of cancer returning?

The risk of cancer returning differs between cancers, and between sub-types of the same cancer.

New screening and treatment options have seen reductions in recurrence rates for many types of cancer. For example, between 2004 and 2019, the risk of colon cancer recurring dropped by 31-68%. It is important to remember that only someone’s treatment team can assess an individual’s personal risk of cancer returning.

For most types of cancer, the highest risk of cancer returning is within the first three years after entering remission. This is because any leftover cancer cells not killed by treatment are likely to start growing again sooner rather than later. Three years after entering remission, recurrence rates for most cancers decrease, meaning that every day that passes lowers the risk of the cancer returning.

Every day that passes also increases the numbers of new discoveries, and cancer drugs being developed.

What about second, unrelated cancers?

Earlier this year, we learned Sarah Ferguson, Duchess of York, had been diagnosed with malignant melanoma (a type of skin cancer) shortly after being treated for breast cancer.

Although details have not been confirmed, this is likely a new cancer that isn’t a recurrence or metastasis of the first one.

Australian research from Queensland and Tasmania shows adults who have had cancer have around a 6-36% higher risk of developing a second primary cancer compared to the risk of cancer in the general population.

Who’s at risk of another, unrelated cancer?

With improvements in cancer diagnosis and treatment, people diagnosed with cancer are living longer than ever. This means they need to consider their long-term health, including their risk of developing another unrelated cancer.

Reasons for such cancers include different types of cancers sharing the same kind of lifestyle, environmental and genetic risk factors.

The increased risk is also likely partly due to the effects that some cancer treatments and imaging procedures have on the body. However, this increased risk is relatively small when compared with the (sometimes lifesaving) benefits of these treatment and procedures.

While a 6-36% greater chance of getting a second, unrelated cancer may seem large, only around 10-12% of participants developed a second cancer in the Australian studies we mentioned. Both had a median follow-up time of around five years.

Similarly, in a large US study only about one in 12 adult cancer patients developed a second type of cancer in the follow-up period (an average of seven years).

The kind of first cancer you had also affects your risk of a second, unrelated cancer, as well as the type of second cancer you are at risk of. For example, in the two Australian studies we mentioned, the risk of a second cancer was greater for people with an initial diagnosis of head and neck cancer, or a haematological (blood) cancer.

People diagnosed with cancer as a child, adolescent or young adult also have a greater risk of a second, unrelated cancer.

What can I do to lower my risk?

Regular follow-up examinations can give peace of mind, and ensure any subsequent cancer is caught early, when there’s the best chance of successful treatment.

Maintenance therapy may be used to reduce the risk of some types of cancer returning. However, despite ongoing research, there are no specific treatments against cancer recurrence or developing a second, unrelated cancer.

But there are things you can do to help lower your general risk of cancer – not smoking, being physically active, eating well, maintaining a healthy body weight, limiting alcohol intake and being sun safe. These all reduce the chance of cancer returning and getting a second cancer.

Sarah Diepstraten, Senior Research Officer, Blood Cells and Blood Cancer Division, Walter and Eliza Hall Institute and Terry Boyle, Senior Lecturer in Cancer Epidemiology, University of South Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

An article published this week in the prestigious journal Nature Medicine documents what is believed to be the first evidence that Alzheimer’s disease can be transmitted from person to person.

The finding arose from long-term follow up of patients who received human growth hormone (hGH) that was taken from brain tissue of deceased donors.

Preparations of donated hGH were used in medicine to treat a variety of conditions from 1959 onwards – including in Australia from the mid 60s.

The practice stopped in 1985 when it was discovered around 200 patients worldwide who had received these donations went on to develop Creuztfeldt-Jakob disease (CJD), which causes a rapidly progressive dementia. This is an otherwise extremely rare condition, affecting roughly one person in a million.

What’s CJD got to do with Alzehimer’s?

CJD is caused by prions: infective particles that are neither bacterial or viral, but consist of abnormally folded proteins that can be transmitted from cell to cell.

Other prion diseases include kuru, a dementia seen in New Guinea tribespeople caused by eating human tissue, scrapie (a disease of sheep) and variant CJD or bovine spongiform encephalopathy, otherwise known as mad cow disease. This raised public health concerns over the eating of beef products in the United Kingdom in the 1980s.

Human growth hormone used to come from donated organs

Human growth hormone (hGH) is produced in the brain by the pituitary gland. Treatments were originally prepared from purified human pituitary tissue.

But because the amount of hGH contained in a single gland is extremely small, any single dose given to any one patient could contain material from around 16,000 donated glands.

An average course of hGH treatment lasts around four years, so the chances of receiving contaminated material – even for a very rare condition such as CJD – became quite high for such people.

hGH is now manufactured synthetically in a laboratory, rather than from human tissue. So this particular mode of CJD transmission is no longer a risk.

What are the latest findings about Alzheimer’s disease?

The Nature Medicine paper provides the first evidence that transmission of Alzheimer’s disease can occur via human-to-human transmission.

The authors examined the outcomes of people who received donated hGH until 1985. They found five such recipients had developed early-onset Alzheimer’s disease.

They considered other explanations for the findings but concluded donated hGH was the likely cause.

Given Alzheimer’s disease is a much more common illness than CJD, the authors presume those who received donated hGH before 1985 may be at higher risk of developing Alzheimer’s disease.

Alzheimer’s disease is caused by presence of two abnormally folded proteins: amyloid and tau. There is increasing evidence these proteins spread in the brain in a similar way to prion diseases. So the mode of transmission the authors propose is certainly plausible.

However, given the amyloid protein deposits in the brain at least 20 years before clinical Alzheimer’s disease develops, there is likely to be a considerable time lag before cases that might arise from the receipt of donated hGH become evident.

When was this process used in Australia?

In Australia, donated pituitary material was used from 1967 to 1985 to treat people with short stature and infertility.

More than 2,000 people received such treatment. Four developed CJD, the last case identified in 1991. All four cases were likely linked to a single contaminated batch.

The risks of any other cases of CJD developing now in pituitary material recipients, so long after the occurrence of the last identified case in Australia, are considered to be incredibly small.

Early-onset Alzheimer’s disease (defined as occurring before the age of 65) is uncommon, accounting for around 5% of all cases. Below the age of 50 it’s rare and likely to have a genetic contribution.

The risk is very low – and you can’t ‘catch’ it like a virus

The Nature Medicine paper identified five cases which were diagnosed in people aged 38 to 55. This is more than could be expected by chance, but still very low in comparison to the total number of patients treated worldwide.

Although the long “incubation period” of Alzheimer’s disease may mean more similar cases may be identified in the future, the absolute risk remains very low. The main scientific interest of the article lies in the fact it’s first to demonstrate that Alzheimer’s disease can be transmitted from person to person in a similar way to prion diseases, rather than in any public health risk.

The authors were keen to emphasise, as I will, that Alzheimer’s cannot be contracted via contact with or providing care to people with Alzheimer’s disease.

Steve Macfarlane, Head of Clinical Services, Dementia Support Australia, & Associate Professor of Psychiatry, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.