Wednesday April 23 2008
The neck and scalp should be included in skin exams.
“Skin cancers on the scalp or neck are more deadly than those elsewhere on the body, a large study has suggested”, BBC News reported. The Daily Telegraph also describes the results of a new study that examined the prognosis (chance of survival) of patients who developed a malignant melanoma on their scalp or neck. The study found that those people with this specific form of cancer in this location were almost twice as likely to die within five years as those who had a similar lesion on an arm or leg.
It is important to stress that this research only applies to the rarer form of skin cancer, malignant melanoma, and not to the more common type, basal cell carcinoma. It should also be pointed out that the research found that scalp and neck melanomas had the poorest prognosis, while melanomas found on the face had a more favourable one. The reasons behind the differences in prognosis are not answered by the study and the researchers call for further studies to shed light on these.
This research is reliable and reinforces the importance of clinicians and nurses including the neck and scalp when examining patients for possible melanoma.
Where did the story come from?
Dr Anne Lachiewicz and colleagues from the Department of Dermatology at the University of North Carolina, and the Department of Internal Medicine at the University of New Mexico, carried out the research. The study was funded in part by grants from the National Cancer Institute. The study was published in the (peer-reviewed) medical journal: Archives of Dermatology.
What kind of scientific study was this?
This was a cohort study based on a retrospective analysis of data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program. The large scale, SEER program collects and publishes cancer incidence and survival data from population-based cancer registries in the US. The researchers restricted their analysis to data from 1992 to 2003 from 13 states, which represented about 14% of the US population. They further restricted their analysis to white, non-Hispanic adults over 20 years of age, who had had their first confirmed case of melanoma.
From the 13 databases, they collected details of just over 15,000 first cases of melanoma and data such as age at diagnosis, tumour thickness, depth of invasion, whether ulcers were present, subtype of tumour and lymph node involvement.
The researchers were interested in the time it took to die from melanoma (for those that died) and were specifically interested in the probability of surviving five or 10 years from diagnosis for scalp and neck melanomas compared with melanomas on other parts of the body. They also used statistical models to analyse the data separately, looking for any characteristics, such as anatomical site or tumour thickness that were known to be associated with a poorer prognosis.
What were the results of the study?
The researchers report that among those in the registry they had complete data on, 43% had melanomas on their arms or legs, 34% on the trunk, 12% on the face or ears, 6% on the scalp or neck and 4% elsewhere.
Those who had scalp or neck melanomas had an 83.1% chance of surviving five years and a 76.2% of surviving 10. This was compared to a 92.1% chance of surviving five years and 88.7% chance of surviving 10 for those with a melanoma on other sites, including the extremities, the trunk, face and ears. The difference was statistically significant.
In their modelling analysis, the researchers took into account a number of factors known to affect survival including age, tumour thickness, sex and ulceration. They found that patients with melanoma of the scalp or neck died of melanoma at 1.84 times the rate of those with melanoma on the extremities.
What interpretations did the researchers draw from these results?
The researchers concluded that their findings have “implications for screening and public
health recommendations”. They urge clinicians and nurses to examine the scalp and neck carefully during routine skin examinations. They suggest that further studies are needed to understand the factors that led to the differences in survival.
What does the NHS Knowledge Service make of this study?
This large registry-based study has clearly shown important differences in survival for people with melanoma, which depends on the location of the melanoma when it was first discovered. Some aspects of this study and those relating to the newspaper reports deserve a mention:
- The study was conducted using data from white, adult populations in some, but not all, US states. The areas that the researchers had data for were described as those with medium rates of melanoma so there is a chance that the conclusions do not apply to other ethnic groups, geographical areas or ages. However, as the researchers themselves point out, it is unlikely that this affects their overall conclusions, which probably apply to all melanomas found on the scalp and neck regardless of ethnicity, area or age.
- The research does not say anything about the more common basal cell carcinomas or squamous cell carcinomas. These are also types of skin cancer, and by using the more general term ‘skin cancer’, misunderstandings could be made.
- The researchers also acknowledge that other forms of bias could have affected the results, such as the bias caused by choosing more (or less) aggressive treatments for tumours found in different parts of the body, but that most of these biases would have resulted in a less pronounced difference between the groups.
Overall, this study helps to resolve some of the debate about the prognosis for melanomas found in different parts of the body. It reinforces the need for a complete head-to-toe inspection - one that includes the scalp and neck - when concern is raised about the possibility of a pigmented mole being a malignant melanoma. Prevention by protecting the scalp and neck from harmful UV solar radiation also seems an obvious and simple precaution.
Sir Muir Gray adds...
This is a good study. Wear a hat in the sun.