Melanoma is the most common primary malignancy arising on the foot [1]. The location has been noted in a number of studies to hold a worse prognosis compared to lesions elsewhere on the body [2] often due advanced disease at diagnosis [3, 4]. It is likely that the time factor is key here - the time taken to reach a diagnosis depends on the patient's ability to recognise and seek professional advice.
Delay in diagnosis
Secondly, diagnosis depends on the professional's capacity to recognise the lesion. Melanoma on the feet are often presented later to clinicians than melanoma elsewhere. Data were available from our study of 37 patients showing that the time from first noticing a lesion to diagnosis was on average 9 months, which shows similarities to other published studies of patients with plantar and foot lesions [5]. Reasons for delayed presentation have been undertaken and includes older age, male gender and lower educational levels all predicting later presentation [6].
How visible is the melanoma?
One aspect which has not been fully explored is how the visibility of the lesion affects the prognosis of melanoma. A study undertaken in New York State by Everdell et al., [7] retrospectively reviewed 3 years of melanoma cases dividing them into non-visible locations (scalp, backs of arms, legs, posterior neck and plantar surface and visible locations). In total 382 patients were compared - 201 with "visible lesions" and 181 with "non-visible lesions". Analysis of the data showed that patients with non-visible lesions were more likely to have stage 3 & 4 cancers as compared to stage 1 and 2 with most visible lesions – 63% of stage 4 melanoma were non-visible.
Implications for practice
This is the first time this aspect of melanoma prognosis has been examined suggesting those melanoma the patient cannot easily see present later, probably because they are discovered later. Of course, an alternative explanation maybe lesions in these areas a histologically more aggressive. Some previous research has suggested lesions located on the upper back, posterior arm, posterior neck and posterior scalp may have a poorer survival [8, 9] likewise there is some work suggestion that acral lentiginous melanoma (most often located on the soles of the feet and in the nails) may have this characteristic too but remains to be fully established.
Ultimately, podiatrists have an important role to continue to screen patients for lesions arising on non-visible parts of the foot and provide suitable education for patients on self-examination. Studies have shown that self-screening is low anyway [10], but even when the patient is self examining, the feet are rarely checked [11].
References
1. Barnes B, Seigler H, Saxby T, Kocher M, Harrelson J: Melanoma of the foot.J Bone Joint Surg Am 1994, 76:892-898.
2. Hsueh E, Lucci A, Qi K, Morton D: Survival of patients with melanoma of the lower extremity decreases with distance from the trunk. Cancer Causes Control 1998, 85:383-388.
3. Adams BE, Peng PD, Williams ML: Melanoma of the Foot Is Associated With Advanced Disease and Poorer Survival. J Foot Ankle Surg 2018, 57:52-55. https://pubmed.ncbi.nlm.nih.gov/29037928/
4. Durbec F, Martin L, Derancourt C, Grange F: Melanoma of the hand and foot: epidemiological, prognostic and genetic features. A systematic review. Br J Dermatol 2012, 166:727-739. https://onlinelibrary.wiley.com/doi/10.1111/j.1365-2133.2011.10772.x
5. Phan A, Touzet S, Dalle S, Ronger-Savle S, Balme B, Thomas L: Acral lentiginous melanoma: a clinicoprognostic study of 126 cases. Br J Dermatol 2006, 155:561-569. https://academic.oup.com/bjd/article-abstract/155/3/561/6636878?redirectedFrom=fulltext&login=false
6. Richard MA, Grob JJ, Avril MF, Delaunay M, Gouvernet J, Wolkenstein P, Souteyrand P, Dreno B, Bonerandi JJ, Dalac S, et al: Delays in diagnosis and melanoma prognosis (I): the role of patients. Int J Cancer 2000, 89:271-279.
7. Everdell E, Shah H, Parisi R, Feustel PJ, Davis L: Non-visibility of Suspicious Lesions by Patients Leads to Later Detection of Melanoma: A Retrospective Analysis. J Am Acad Dermatol 2023.
8. Weinstock MA, Morris BT, Lederman JS, Bleicher P, Fitzpatrick TB, Sober AJ: Effect of BANS location on the prognosis of clinical stage I melanoma: new data and meta-analysis. Br J Dermatol 1988, 119:559-565.
9. Bernengo MG, Reali UM, Doveil GC, Cappello N, Lisa F, Moretti S: BANS: a discussion of the problem. Melanoma Res 1992, 2.
10. Hamidi R, Peng D, Cockburn M: Efficacy of skin self-examination for the early detection of melanoma. Int J Dermatol 2010, 49:126-134.
11. Tsai MS, Chiu MW: Patient-reported frequency of acral surface inspection during skin examination in white and ethnic minority patients. J Am Acad Dermatol 2014, 71:249-255.