Factors involved in presentation of older people with thick melanoma

Pauline F Hanrahan, Peter Hersey and Catherine A D'Este

MJA 1998; 169: 410-414
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Abstract - Introduction - Methods - Results - Discussion - Acknowledgements - References - Authors' details
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Abstract	Objective: To examine whether presentation of older people with thick melanoma is a result of the site and histological type or of their reduced ability to identify melanoma. Design and setting: Retrospective analysis of the Newcastle Melanoma Unit patient database. Patients: 2154 patients with melanoma for whom complete data (histological type, thickness and site of melanoma) were available and who presented from February 1981 to April 1997. Main outcome measures: Histological type and site of melanoma in older (50 years) versus younger men and women; frequency with which these groups identified melanoma and the first changes of melanoma that were noticed. Results: Patients aged 50 years, particularly men, were more likely to present with thicker lesions. Older men and, to a lesser extent, older women were more likely to present with nodular melanoma, which were more frequent on the scalp and face in older, compared with younger, men, and scalp and back in older men compared with older women. Failure to identify melanoma was associated with older age, sites on the scalp and back and histological type of the lesion, but was independent of sex once histological type, age, site and thickness were taken into account. Multivariate analysis indicated that the association of older age of patients with failure to identify melanoma applied irrespective of the site, type and thickness of their melanoma. Conclusion:. The higher frequency of thick melanoma in older people is accounted for by an increased proportion of nodular melanoma and decreased ability to recognise the changes of melanoma. These findings have important implications for examination of older patients by doctors and for design of strategies for early detection of melanoma in this age group.
Introduction	Survival from melanoma is related to thickness of the tumour. Ninety-six per cent of patients whose lesions are detected early (< 0.75 mm thick) will survive to 10 years,1,2 but this decreases to 50% for patients with lesions 4 mm or greater.3,4 Previous studies have shown that most patients who present with thick lesions are men aged over 50 years.5-7 In New South Wales over 50% of deaths from melanoma involve men over 50, even though this group comprises only 12%-14% of the population.8 Clearly, strategies that facilitate early detection of melanoma in older men may markedly reduce the death rate from this cancer. We have previously investigated the ability of older men to distinguish between benign and malignant pigmented skin lesions in photographs and whether an educational brochure assists this ability;9 the brochure increased knowledge of melanoma, but did not help participants distinguish between benign and malignant pigmented skin lesions. We then investigated whether this age group had inherent difficulties in recognising the changes of melanoma and found that all age groups had difficulty in recognising the appearance of new pigmented lesions and changes in lesions over time.10,11 Older people were no less able than younger people to identify change, but falsely identified changes in unchanged lesions more frequently. In this study we sought to examine factors associated with failure of patients to identify their melanoma and the importance of this in presentation of older patients with thick melanoma.
Methods	Information for the study was obtained from the database in the Newcastle Melanoma Unit (NMU), which was established in 1981 and is a referral centre for patients from the Hunter region of New South Wales. Over 90% of patients with melanoma in the Hunter region attend the unit. The database contains information obtained by experienced oncology nurses who interview patients, asking questions about changes they had noticed leading to diagnosis of melanoma, for how long they had noticed the changes and whether these were in a pre-existing or new lesion. The age and sex of patients, site of their primary lesion, its histological type and thickness were also recorded. Histological investigation of the lesions was reviewed by at least two pathologists and reported as described previously.12 Patient clinical data were entered into a program developed jointly by the Sydney Melanoma Unit and the Macquarie University using Clinical Reporting Systems software (Brisbane Road, Castle Hill, NSW). We included data for all patients presenting to the NMU between February 1981 and April 1997. The data were categorised for statistical analysis as follows. Patients were divided into two groups by age (< 50 and 50). As in a previous study,5 thickness of primary lesions was categorised as < 3 mm, or 3 mm. Data on the site of the primary melanoma were divided into seven categories (scalp, face, neck, back, anterior trunk, arm and leg). Melanomas were categorised into seven histological types (superficial spreading melanoma [SSM], nodular melanoma [NM], lentigo maligna [LM], in-situ melanoma, desmoplastic melanoma, unknown, and unclassified) of which we included only the first three relatively common types. Categories for types of changes were: unidentified (including instances where patients were uncertain whether a change had occurred, or said that no change had occurred, but melanoma was detected by their general practitioners or other doctors); size and shape; colour; changes in sensation (eg, itching, tingling); and bleeding.
Statistical analysis	Data were analysed with SAS13 and STATA14 statistical software. Lesion characteristics (thickness, histological type and site of melanoma) were compared by age and by sex separately using chi-squared analyses. Lesion characteristics and age and sex were also compared for those who had, and had not, identified any changes. Logistic regression analyses were performed to examine factors associated with identification of any changes of melanoma, using any change versus no change, as the outcome variable. All five independent variables were tested for significance by forward stepwise regression analysis. After the final main effects model was obtained, all possible interactions were tested. The likelihood ratio statistic was used to assess statistical significance in the logistic regression analyses. We also tested (by chi-squared analysis) lesion characteristics, age and sex for association with type of changes noticed; 95% confidence intervals (CI) were calculated for each type of change. A significance level of 0.05 was used for all analyses. Subgroups were considered to differ significantly if 95% CIs did not overlap.
Results	The database included records for 3435 patients who attended the NMU during the study period. Exclusions included: 932 patients for whom there was incomplete data or for whom data could not be appropriately classified; 325 with uncommon, unknown, desmoplastic or unclassified histological types of melanoma; and 22 with melanoma at unusual sites (eg, mucosal regions, buttocks, groin). The final sample of 2154 patients comprised 1144 men (53%) and 1010 women (47%); 1142 patients (53%) were aged 50 years or over and 59% of the men in the study were in this age group, compared with 46% of the women. There were no significant differences in sex or age of patients excluded compared with those included (sex: chi-squared = 0.006, df = 1, P = 0.94; age: chi-squared = 1.7, df = 1, P = 0.18). The site and thickness of melanomas were similar in those excluded and included. Excluded patients had a different distribution of histological types (as this was part of the basis for their exclusion) and a higher proportion of unnoticed changes than those included. More detailed information about excluded patients is available from the authors.
Lesion characteristics	Thickness: Box 1 shows that patients aged 50 years or over (14.5%; 95% CI, 12%-16%) were significantly more likely to present with thick lesions than younger patients (4.7%; 95% CI, 3%-6%), and men (12%; 95% CI, 10%-14%) were more likely to have thick lesions than women (7%; 95% CI, 6%-9%). Site: Melanoma was found most often on the backs of male patients (47%; 95% CI, 45%-50% v. 24%; 95% CI, 22%-27% for women), whereas the leg was the predominant site in women (38%; 95% CI, 35%-41% v. 16%; 95% CI, 13%-18% for men). The incidence of melanoma on the scalp, face and neck was similar for men and women. Melanoma on the arms was more common in women (19%; 95% CI, 16%-21% v. 12%; 95% CI, 10%-13% for men), while melanoma on the face was more common in older patients and melanoma on the anterior trunk and leg was more common in younger men than older men. Melanomas were more common on the scalp and face in older, compared with younger, men and more common on the scalp and back of older men compared with older women (Box 1). Histological type: SSM was more common in younger patients of both sexes and NM was more common in older male patients. Most thin lesions (80%) were SSM and most thick lesions (72%) were NM. Thicknesses of the three histological types were: SSM, 0.02-10.5 mm (median, 0.63 mm; interquartile range [IQR], 0.4-1.0 mm); NM, 0.2-25 mm (median, 2.46 mm; IQR, 1.4-3.8 mm); and LM, 0.1-8.5 mm (median, 0.4 mm; IQR, 0.25-0.8 mm).
Factors associated with failure to identify melanoma	Many melanomas were not detected by patients, but were identified by their doctors. Sex and age: Men were more likely to fail to notice changes of melanoma than women (37%; 95% CI, 35%-49% v. 30%; 95% CI, 28%-32%) as were older, compared with younger, people (38%; 95% CI, 35%-41% v. 28%; 95% CI, 25%-31%). As shown in Box 2, a greater proportion of older men failed to identify changes in their lesions than younger men; the same trend was evident in women. Site: Patients most frequently failed to identify changes in lesions on the scalp (42%; 95% CI, 30%-52%) and back (41%; 95% CI, 37%-45%), but even among patients with a lesion on the face, 31% (95% CI, 26%-33%) did not identify it as melanoma. The anterior trunk was the least common site for unidentified change (24%; 95% CI, 20%-28%). Older patients failed to identify changes more often than younger patients for all sites except the face and scalp, where the reverse was the case (Box 2). However, numbers are very small for these groups and results should be interpreted with caution. Histological type: A greater proportion of patients with LM (47%; 95% CI, 40%-55%) failed to identify their melanoma than patients with SSM (33%; 95% CI, 31%-35%) or NM (29%; 95% CI, 25%-33%), although by the time they were detected the NM were much thicker. Older people were less likely than younger people to identify melanoma of all three histological types. Regression analyses: Age, thickness, histological type and site of lesion were significantly associated with identifying changes (Box 3). After these variables were included in the model, sex was no longer statistically significant. After adjustment for other variables in the model, the odds of older people identifying changes was two-thirds the odds of younger people identifying changes, and the odds of those with thicker lesions identifying changes was one-and-a-half times the odds of those with thinner lesions identifying changes. Those with LM had about half the odds of identifying changes as those with NM. As shown in Box 3, those with lesions on the face, arm, anterior trunk and leg had significantly higher odds of identifying changes than those with lesions on the back (reference group).
Associations with thick melanoma (3 mm)	As shown in Box 3, age and nodular melanoma were strongly associated with presentation with thick lesions. Changes of melanoma were more frequently identified in thick lesions, but as shown in Box 2, older people were less able to identify melanoma, irrespective of its thickness. It was also of interest that once the histological type of the lesion was taken into account, the site of the melanoma and sex of the patient were no longer related to thickness (ie, thick melanoma on the back and scalp in men appeared to result from the higher frequency of NM at these sites in men; see Box 3).
Types of changes reported by patients	Significantly fewer older than younger men reported changes in size and shape (21% v. 30%). The same was true for colour (20% v. 27%), and twice as many older men stated that the first change they were aware of in their skin lesion was bleeding (7% v. 3%). However, these differences were not statistically significant. Similarly, our findings that more younger than older women reported colour changes as the first change noticed (32% v. 25%) and (in contrast to men) older women reported changes in size and shape as the first change as frequently as younger women (30% v. 28%), were also not statistically significant. As shown in Box 4, patients with NM reported changes in colour significantly less frequently than those with SSM, change in sensation significantly more frequently than those with LM, and bleeding significantly more frequently than those with LM and SSM. Changes in size and shape were the most frequent changes reported in thick melanoma (34%), whereas changes in colour were more frequently reported in thin lesions (27%). Bleeding was reported as the first change significantly more frequently in thick than thin lesions (17% v. 4%). Reported changes in sensation were similar for thick or thin lesions.
Discussion	We excluded approximately one-third of the patients on the NMU database, mainly because of missing information about changes noticed or thickness measurements, or because they had melanoma of unusual histological type or location. However, the excluded patients appeared to have similar age and sex distribution, site and thickness measurements to patients in the study. Nonetheless, our results may not be generalisable to patients with the less common histological types of melanoma. Forty per cent of men and 34% of women aged over 50 failed to identify their melanoma. In contrast, younger patients of both sexes reported changes of melanoma in over 70% of cases. These findings were consistent with those of Koh et al15 who found that 38% of melanomas were not identified by men over the age of 60, compared with 23% in men less than 40 years of age. We also found that failure to detect melanoma was not only related to the age of the patient, but was associated with the site and type of the melanoma. Firstly, older men had lesions at sites which are more difficult to see, such as the back and scalp, with nearly 50% of melanoma in older men (compared with only 20% in older women) occurring on the back. Other series have reported similar differences in site distribution of melanoma between the sexes.16,17 Secondly, compared with younger people, older people, particularly men, had a higher proportion of NM, similar to that reported elsewhere.5,18 Patients also identified NMs when they were much thicker than SSMs (median, 2.46 mm v. 0.63 mm). The higher frequency of bleeding as the first change noted in patients with NM was consistent with this finding.19 The higher proportion of NM in older people and more frequent occurrence in "hard-to-see" sites could solely explain the presentation of older people with thicker melanomas. However, regression analysis indicated that for any given thickness and type of melanoma at a given site, older people were less able to recognise melanoma than younger people. In our examination of the first change that drew the attention of patients to their melanoma, we found that self-reporting of a change in colour was infrequent in patients with thick melanoma, and in patients with NM relative to those with SSM. These results were surprising, as previous studies have shown that changes in colour were one of the most frequent early changes of melanoma.20,21 Most of the thick melanoma were NM, which tend to be relatively homogeneous in colour compared with SSM. Thus, the different patterns of colour between NM and SSM may need to be emphasised in educational material directed at older patients. Bleeding was clearly associated with thick and nodular melanoma, but this is a late rather than an early sign.19 To the best of our knowledge this is the first study that has sought to identify reasons why older people present with thicker melanoma. The finding that older patients had lower ability to detect melanoma than younger people is consistent with our previous findings that older people had difficulty in discriminating early changes of melanoma in photographs of pigmented lesions.10,11 Previous studies have noted that younger people were more likely to rate change in skin lesions as extremely important in diagnosis of melanoma than older respondents.22 Older people may also not inspect their skin as frequently as younger people and this may contribute to their lower rate of detection of melanoma. Our findings raise questions about the likely effectiveness for older people of public health strategies that rely on self-detection of melanoma. It seems that that greater reliance will need to be placed on detection of melanoma in this age group by health professionals, who may need to be made aware of the high frequency of thick melanoma and characteristics of melanoma in this age group. Our previous studies have shown that recognition of change in existing lesions over time or the appearance of new pigmented skin lesions can be very difficult, but is assisted by whole-body photographs.10,11 The feasibility of using whole-body photographs to help general practitioners detect melanoma is currently under evaluation in a project funded by the National Health and Medical Research Council.
Acknowledgements	We thank the nursing sisters Sue Collins, Debbie Bradley, Donna Owens and Kathy Hall for collection of the data and Vicky Hunter for data entry. Dr Hanrahan was supported in part by the Hunter Melanoma Foundation.
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Authors' details

Centre for Clinical Epidemiology and Biostatistics, University of Newcastle, Newcastle, NSW.
Catherine A D'Este, BMath, PhD, Lecturer in Biostatistics, Faculty of Medicine and Health Sciences.

Reprints will not be available from the authors.
Correspondence: Dr P Hersey, Room 443, David Maddison Clinical Sciences Building, Cnr King and Watt Streets, Newcastle, NSW 2300.