Recurrence rates after functional surgery versus amputation for nail squamous cell carcinoma not involving the bone: A systematic review

Introduction

Nail unit squamous cell carcinoma (nSCC) represents a relatively unusual cutaneous squamous cell carcinoma variation that requires prompt diagnosis and appropriate surgical treatment. Traditionally, amputation was the standard therapy for nail unit malignancies.¹ While amputation provides significant local control, it also causes remarkable physical and cosmetic damage, particularly in finger lesions. In recent years, researchers have demonstrated that functional surgery is a reliable therapeutic option that provides better function and cosmetic benefits than amputation. This is especially true in cases with nSCC without bone invasion. Functional surgery may provide successful management of minimally invasive tumours in the absence of additional negative prognostic factors. This systematic review of current studies summarises the local recurrence rates following functional surgery and amputation respectively, in nSCC without bone involvement.

Methods

Data extraction process

Three investigators (HS.W., F. L., and JY.J.) independently reviewed the titles and abstracts of the included publications before evaluating the complete articles for eligibility [Figure 1]. Following inclusion, the three authors (HS.W., F.L. and SD.H.) independently retrieved data on the treatment method, recurrence, and follow-up duration. Any disagreements were handled via a consensus meeting with the third investigator (DG.W.). Following inclusion, information gathered from every article was retrieved and subcategorized, encompassing the year of publication, period, number of patients, age, gender distribution, tumour stage, kind of intervention, number of recurrences, and follow-up duration.

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Figure 1:

PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flow chart of study selection.

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Results

Discussion

The nail apparatus has a rather complex anatomical structure. A good understanding of its structure is required to diagnose and manage entities involving this organ. Malignant nail tumours are typically rare with nSCC being the most common carcinoma reported. When nSCC is present, the nail unit might appear in a variety of clinical presentations. Despite being the most prevalent malignant subungual tumour, nSCC is frequently misdiagnosed as an innocuous condition like onychomycosis, verruca vulgaris, or trauma-induced nail dystrophy.¹³ Middle-aged males are more likely to be affected, and the hand is the most commonly reported area.⁴ A high level of suspicion is therefore required when addressing a nail condition to avoid a delay in diagnosis, which may complicate therapy and significantly affect the prognosis. While metastasis and mortality are uncommon in nSCC, early biopsies of chronic non-healing and persistent lesions may merit a better prognosis.⁴ Clinicians in practice should therefore be aware of benign-presenting nail lesions that do not improve with appropriate management and should suggest that patients undergo nail biopsies when applicable.

Functional procedures, such as Mohs micrographic surgery and wide surgical excision, were routinely tested to establish the best first-line treatment for nSCC. However, the existing research does not recommend a specific therapeutic strategy as the first line of therapy. Studies conducted over the last decade have shown that more conservative approaches for nSCC management are preferable to traditional amputation. These authors believe that traditional amputations may result in functional problems, undesirable cosmetic results, and possibly psychological distress. This is particularly noticeable in the amputation of the thumb, which accounts for about 40% of the hand’s normal function.¹⁴ Further, the patient may experience loss of sensation at the amputated site, unusual pains, excessive sensitivity, and difficulties when gripping small items, which may interfere with daily tasks.^8,15

Mohs micrographic surgery has the advantage of eliminating the tumour with histological confirmation of the actual extent of malignancy, as well as removing the diseased tissue while preserving its normal structure.^3,12,16 Preserving the viable tissues of the finger to the greatest extent feasible is critical for a functioning digit.⁸ However, imaging methods typically fail to detect the depth of nSCC invasion. Mohs micrographic surgery can detect periosteal invasion and accurately differentiate bone invasion from inflammation or compression.^8,12 In general, Mohs micrographic surgery is an outstanding option for tumour removal, but it is somewhat more complicated and demanding, it also requires a skilled and certified Mohs surgeon.¹⁷

Because Mohs micrographic surgery is too difficult to perform on the nail apparatus due to its unique anatomical structure, a few studies have highlighted the utility of the wide surgical excision method for nSCC.^4,6,10,15 Flores et al. discovered that wide surgical excision with a margin of 5 mm was correlated with a reduced recurrence rate and gave greater functional and aesthetic advantages than amputation.¹⁵ Surgical wounds may be left to heal by secondary intention, or with fillers, full-thickness skin grafts or skin flaps, and all have favourable outcomes.^10,18 Surgical procedures for wide surgical excision are more time-efficient and have been correlated with high patient satisfaction, successful recovery, and effective local disease control.¹⁵ On the other hand, wide surgical excision removes more viable tissues, causing poor functional and aesthetic outcomes for smaller tumours where the nail unit might potentially be partially retained.¹¹ The extent of the tumour generally remains unknown until the procedure is completed; hence, the margin of resection as well as the best time to do reconstruction are uncertain. Nevertheless, late recurrence of nSCC is frequent after both types of surgical procedures which had completely removed the carcinoma.⁶

Consistent with previous studies, this review also showed a male predominance around the age of 60. Lesions were mainly on fingernails. Our systematic review shows that functional surgery of the nail unit is an effective alternative to amputation in nSCC that does not involve the bone. In this study, we included Mohs micrographic surgery, wide surgical excision, and local surgical excision in our understanding of functional surgery. Unlike Mohs micrographic surgery and wide surgical excision, local surgical excision has a relatively high recurrence rate.^4,11 This could be a result of tumour clearance being insufficient. As such, we do not think it is a desirable treatment for nSCC lesions because it only removes the portion of the tumour observable by the naked eye.^4,11

Regardless of the surgical type, attaining histological clearance should be the gold standard of treatment for nSCC, whether it involves the bone or not. To achieve complete excision, a thorough histologic assessment of the surgical margins is required in all instances. In our opinion, efficient treatment is determined by the total elimination of the tumour rather than by an aggressive surgical approach. Simultaneously, the surgical technique should be sufficient to ensure total tumour excision while preserving the normal function of the finger or toe. This suggests that wide surgical excision and Mohs micrographic surgery should be desirable options for a significant number of nSCC patients since both have been associated with low recurrence rates.¹⁷ Further prospective studies comparing these two techniques are necessary to determine whether Mohs micrographic surgery or wide surgical excision is the preferable intervention for nSCC that does not involve the bone.

Limitations

There are several drawbacks in this review. First, only retrospective observational studies were evaluated in this analysis; hence, there may be missing data such as those caused by recall bias. Second, the number of studies may be too small for a meta-analysis. Third, the follow-up period in the recruited studies was modest, perhaps underestimating the probability of recurrence of this slow-growing neoplasm. Because of the distinctive nail structure and the associated difficulty in achieving clear surgical margins, functional surgery is more complicated than amputation. As a result, surgeons with minimal nail surgery experience may be limited in their use of functional surgery. Despite these limitations, given the rarity of nSCC and the lack of controlled trials, this review might be informative for clinicians who are treating patients with this carcinoma, and may help in planning bigger trials.

Conclusion

There is no consensus on the surgical management of nSCC that does not involve the bone. The recurrence rates of functional surgery and amputation do not differ significantly, as seen in our review. To reduce severe functional limitations and psychological discomfort following amputation, functional surgery should be considered as a first-line therapy for those without bone involvement. When functional surgery fails to establish clean margins, amputation should be considered as a last option. To date, only small cohorts or case reports dealing with this nail neoplasm have been published. Further research comparing these two procedures with large sample sizes is required to give firm evidence on whether Mohs micrographic surgery or wide surgical excision is a better surgical alternative.