“Men who live alone at greater skin cancer risk,” The Daily Telegraph reports.
The headlines are based on a population study from Sweden, which followed almost 30,000 people diagnosed with malignant melanoma – the most serious form of skin cancer.
Despite the headline, the study did not find that men who live alone were at greater risk of developing melanoma.
Rather, it found that in men who did develop melanoma, those living by themselves were 40% more likely to have had a more advanced stage of disease at the time of diagnosis. Men living alone were also less likely to survive the disease.
These links were significant even after adjusting for age, sociodemographics and melanoma characteristics.
There are some limitations, including that that the study has examined only a Swedish population, which may have both genetic as well as climate-related implications.
Nevertheless, a link between living alone and delayed diagnosis seems plausible. If someone lives with a partner they may be more likely to discuss a suspect mole with them; the partner may encourage them to see a doctor; or the partner may notice a mole that the person would not otherwise have done.
Overall the study highlights the need for us all to be vigilant about any suspicious moles or marks on the skin. Melanoma can be an aggressive cancer, and a good outcome relies on early diagnosis and treatment.
Where did the story come from?
The study was carried out by researchers from the Karolinska Institutet and other academic institutions in Sweden, and was funded by the Swedish Cancer Society, the Radiumhemmet Research Funds, the Sigurd and Elsa Goljes Memorial Foundation and that Stockholm County Council.
The study was published in the peer reviewed Journal of Clinical Oncology.
The Telegraph article gives accurate coverage of this study, though it is important that the headline – “Men who live alone at greater skin cancer risk” – is not misinterpreted.
It is not that men who live alone had a greater risk of actually developing melanoma. Instead it is that if they had developed melanoma, they were more likely to be diagnosed at a later stage than if they lived with someone.
What kind of research was this?
This was a Swedish population study which aimed to see whether in people with malignant melanoma, disease stage at the time of diagnosis and disease survival were associated with whether the person lived alone or with someone else. As the researchers say, previous studies suggest that social support and marital status have an influence on survival from a range of cancers.
Melanoma is the most serious type of skin cancer. It can be very aggressive and spread rapidly to the lymph nodes and elsewhere in the body. A good outcome relies on diagnosis and treatment as early as possible.
What did the research involve?
This research used the Swedish Melanoma Register to identify 27,235 people diagnosed with malignant melanoma between 1990 and 2007. They only included people with melanoma on the skin (cutaneous malignant melanoma), excluding the people with the rarer types of melanoma that develop elsewhere in the body (for example in the pigment cells in the eye). These people were followed up to death, emigration, development of a new melanoma, or the end of follow-up in December 2012, whichever came first.
The researchers collected information from the registry on each person’s tumour characteristics and treatment. They also documented whether each person lived with a partner or lived alone at the time they were diagnosed (marriage status was not considered). Single people who lived with children were classed as living alone, as it was thought that children could not help contribute to early cancer diagnosis.
The researchers looked at melanoma survival rates according to cohabitation status.
They adjusted their analyses for possible confounding factors such as:
- educational level (used as the main indicator of socioeconomic status)
- living area (metropolitan, urban or rural)
- year of diagnosis
- various tumour characteristics (including tumour site, staging information and laboratory findings)
What were the basic results?
People in the study were diagnosed with melanoma at average age of 62 years and the average follow-up period was eight years. Overall the five-year cancer survival rate for all people in the study was 92% for women and 85% for men.
Among people with a partner the average age at diagnosis was lower for women (55 years) than men (64 years). Among single people average age at diagnosis was higher for women (68 years) than men (63 years).
Across all age groups, a higher proportion of single men had more advanced melanoma at the time of diagnosis than cohabitating men. In women, a difference in melanoma stage at diagnosis according to whether they were single or cohabitating was only seen in women above the age of 70.
After adjusting for confounding factors, single men were around 40% more likely to be diagnosed with a more advanced tumour stage than men living with a partner.
The difference in risk was similar when comparing diagnoses in the earlier stages of diseases (odds ratio [OR] 1.42 95% confidence interval [CI] 1.29 to 1.57 for being diagnosed with stage II rather than stage I), and when comparing the later stages of disease with early stage disease (OR 1.43 [95% CI 1.14 to 1.79] for being diagnosed with stage III or stage IV rather than stage I).
Single women were 15% more likely than women living with a partner to be diagnosed with stage II than stage I cancer (OR 1.15, 95% CI 1.04 to 1.28). But no associations with cohabitation status were seen for more later disease stages.
When looking at survival, after adjustment for all measured confounders including the characteristics of the melanoma at diagnosis, single men were 31% more likely to die from the disease than men living with a partner (hazard ratio 1.31, 95% CI 1.18 to 1.46).
Cohabitation status had no significant effect on survival in women.
How did the researchers interpret the results?
The researchers conclude that across men of all ages, living alone is associated with reduced survival from malignant melanoma, which can be partially attributed to being diagnosed at a more advanced disease stage. They say “this emphasizes the need for improved prevention and early detection strategies for this group”.
This Swedish research benefits from including a very large population sample of people with malignant melanoma – almost 30,000 people diagnosed over a 17 year period.
It also benefits from using a registry, which would be expected to contain reliable information on patient and cancer characteristics, and it has adjusted their analyses for these various confounders.
It finds a clear link that men who lived alone were consistently more likely than men who lived with a partner to have melanoma that was at a more advanced stage at the time of diagnosis and to have poorer survival outlook. The poorer survival outlook may be expected to be a result of the later stage at diagnosis, although interestingly single men were still at increased risk of dying from melanoma even after disease characteristics at the time of diagnosis had been adjusted for.
Women living alone were more likely to be diagnosed with stage II rather than stage I cancer, but no association was found with later stage cancer. Cohabitation status had no significant effect on survival in women with melanoma.
The link does seem plausible. For example, if someone lives with a partner they may be more likely to discuss a suspect mole with them; the partner may encourage them to see a doctor; or the partner may notice a mole that the person would not otherwise have done. All of these things are possible explanations for why men living alone may be diagnosed at a later stage.
However, there are limitations to bear in mind. The study has only assessed whether the person lived alone or with a partner at the time of diagnosis. It is not known how long they had lived with this person, and the nature of this relationship is not known. Also, though the researchers have taken into account as many confounders as possible, there may be a range of unmeasured health and lifestyle factors that may be involved in the relationship. For example, we don’t know how much UV exposure people were getting, and whether there was any difference between single and cohabiting people in their level of exposure, or how much care they took to protect their skin in sunlight.
Also, importantly the study was conducted in Sweden where people, as a broad generalisation, can be fair skinned. They may also get less intense sun exposure in the far Northern hemisphere than people born in hotter climes – though nothing is of course known about travel abroad (which could again differ between single and cohabiting people). These factors may mean that the results may not be the same in people living in other countries.
Overall the study highlights the need for us all to be vigilant about any suspicious moles or marks on the skin. Melanoma can be an aggressive cancer, and a good outcome relies on diagnosis and treatment as early as possible.