Pilonidal Sinus Disease And Carcinoma Prevalence
Overview
This study aimed to evaluate survival and recurrence rates in pilonidal sinus disease (PSD) carcinoma. A retrospective analysis of global literature identified 140 cases published between 1900 and 2022. Survival rates were 61.7% at 3 years, 59.8% at 5 years, and 53.2% at 10 years. Stages I and II exhibited better survival (80.0%) than stage III (70.8%) and stage IV (47.8%) (p = 0.01). G1-tumor 5-year survival was 70.5%, while G2 and G3 were 32.0% (p = 0.002). Recurrence occurred in 46.6%, with an average time-to-recurrence of 15.1 months (1–132 months). Recurrent tumors showed 75.6% local, 33.3% regional, and 28.9% distant recurrence. Poor prognostic factors include advanced-stage disease and poor differentiation.
Introduction
Pilonidal sinus disease (PSD) is a prevalent condition in surgical practice. Occasional cases exhibit malignant changes, a rarity at approximately 0.1% of patients. Notably, only around 140 cases have been documented in the literature. Squamous cell carcinoma (SCC) dominates pilonidal sinus disease carcinoma (PSDCA), followed by basal cell carcinoma and mixed-type carcinoma. Published research indicates a 5-year survival rate of 55%–61%, considerably lower than primary cutaneous squamous cell carcinoma (cSCC).
Remarkably, thorough analyses of survival data have been lacking, with gaps in knowledge, particularly for poorly differentiated carcinomas and those undergoing adjuvant therapy. This study presents a survival analysis of published PSDCA cases, aiming to unravel insights into the disease’s behavior and prognosis.
Method
Inclusion Criteria
This study encompassed all case reports and case series delineating patients in whom carcinoma had developed as a secondary manifestation of pilonidal sinus disease (PSD). The selected articles were scrutinized for relevance to the investigation.
Exclusion Criteria
Cases involving carcinomas that developed within pilonidal areas devoid of any preceding evidence of pilonidal disease (primary skin neoplasms) were excluded from the analysis. Furthermore, reports lacking follow-up data were omitted from the final examination.
Data Collection and Organization
The search was conducted within a spectrum of reputable online medical databases, including PubMed, ScienceDirect, Scopus, Medline, Web of Science, Cochrane, and Google Scholar. Various combinations of keywords, such as “pilonidal AND sinus AND carcinoma,” were employed to ensure comprehensive coverage. Supplementary articles that did not surface in the online databases were identified by scrutinizing contextual information and reference lists within each article.
Extracted Data Sets
Data pertaining to each case were meticulously gathered and structured employing Microsoft Excel (Microsoft® Excel 2019, Version 16.0.11901.20170). The comprehensive datasets for each case incorporated essential information, including demographics (age and gender), histological attributes (type, grade), tumor stage (size, local invasiveness, regional or distant metastases), implementation of adjuvant therapy, outcomes (cure, recurrence, and related temporal and anatomical details, mortality and causal specifics), and duration of follow-up.
Survival Analysis and Statistical Methodology
For survival analysis, Kaplan–Meier curves were formulated through GraphPad‐Prism (GraphPad Software, LLC ® 2021; Version 9.3.1 [471]). Subgroup comparisons were subjected to p-value calculations employing the same software. Given the limited sample size, statistical significance determination relied upon the log‐rank Mantel–Cox test.
Ethical Considerations
This literature-based exploration was granted exemption from ethical approval requisites by the ethical commission of the Medical Association of Lower Saxony.
Results
Study Cohort and Patient Characteristics
The literature exploration revealed 140 relevant cases of pilonidal sinus carcinoma, distributed across 103 global papers from 1900 to 2022. After excluding 29 cases without follow-up data, the final analysis encompassed 111 cases. The patients’ ages ranged from 19 to 86 years, with a mean ± standard deviation of 54.0 ± 11.5 years. Only 9% (n = 10/111) of patients were female. Squamous cell carcinoma (SCC) constituted 94.6% (n = 105/111) of cases. Tumor grade details were unavailable for 51.4% of cases. Among cases with known grades, tumors were well differentiated in 64.8% (n = 35/54), moderately differentiated in 29.6% (n = 16/54), and poorly differentiated in 5.6% (n = 3/54).
Tumor Staging and Treatment
Tumor, nodes, metastases (TNM) stage, based on the Union for International Cancer Control (UICC) system, revealed stages I, II, III, and IV in 3.1% (n = 3/96), 5.2% (n = 5/96), 47.9% (n = 46/96), and 43.8% (n = 42/96) of cases, respectively. Approximately 9.0% (n = 10/111) of patients received palliative therapy due to various reasons, while 91.0% (n = 101/111) underwent curative treatment, with 29.7% (n = 30/101) receiving adjuvant therapy.
Survival Analysis and Recurrence
The follow-up period ranged widely from 1 month to 18 years, averaging 3.4 years. Locoregional recurrence occurred in 46.6% (n = 47/101) of patients treated with curative intent. The time-to-recurrence averaged 15.1 months, with local, regional, and distant recurrence observed in 75.6%, 33.3%, and 28.9% of recurrent tumors, respectively.
Disease-Specific Survival Analysis
Disease-specific survival rates, analyzed using Kaplan-Meier curves, were 61.7% for 3 years, 59.8% for 5 years, and 53.2% for 10 years. Gender did not significantly affect survival. Patients with stage I and II disease exhibited a 5-year survival of 80.0%, while stage III and IV showed 70.8% and 47.8% survival, respectively. Well-differentiated tumors (G1) had a 5-year survival of 70.5%, while G2 and G3 tumors demonstrated 32.0% survival.
Adjuvant Therapy and Recurrence-Free Survival
Comparing patients who received adjuvant therapy with those who didn’t, the 5-year recurrence-free survival was 54.4% versus 52.9%, respectively, with no significant difference (p = 0.73). The 5-year survival in the adjuvant therapy group was 43.9%, slightly worse than the non-adjuvant therapy group.
Conclusion
The journey of understanding pilonidal sinus carcinoma (PSDCA) began in 1900 with Dr. Heinrich Wolff’s report from Germany, unveiling a squamous cell carcinoma (SCC) detected after a PSD recurrence. Subsequent sporadic global reports underscored PSDCA’s aggressive course and poorer prognosis compared to primary cutaneous SCC. Despite this awareness, precise survival rates remained elusive due to the challenge of amassing a sufficient case pool for analysis.
This exhaustive literature search meticulously compiled data from 111 reports with follow-up information on PSDCA cases. The resultant survival analysis yielded a 5-year survival rate of 59.8%. This aligns with Wronski’s estimations, affirming an anticipated 5-year survival range of 55% to 61%. Subgroup analysis delineated a stark survival contrast, with stage IV disease demonstrating 47.8% survival, and moderately and poorly differentiated tumors showing 32.0%.
While advanced disease serves as an established poor prognostic factor in PSDCA, interpreting tumor grade was often complicated by a small sample size. Inconsistencies emerged, with some studies finding no direct link between tumor differentiation and survival, a notion termed an “unexpected finding.” The study’s observation of long-term survival being lower in the well-differentiated group was attributed to cases with unavailable data being predominantly well-differentiated, potentially balancing this discrepancy.
Comparisons were drawn with cutaneous SCC (cSCC), highlighting shared poor prognostic factors. However, PSDCA exhibited notably worse overall prognosis than cSCC, even in early stages or well-differentiated cases. PSDCA defies the characterization of “easily curable” that cSCC often receives, instead manifesting as a more aggressive entity.
Numerous mechanisms potentially explain PSDCA’s aggression compared to cSCC. Factors include challenges in excising locally advanced tumors deeply infiltrating soft tissues or bone. Chronic infection, inflammation, and local scarring might hinder the immune system’s ability to recognize tumor cells as foreign, facilitating progression. Anatomical and mechanical factors, such as fistula tracts, continuous shear forces, and pressure, could expedite metastasis.
Surprisingly, adjuvant treatment’s benefit in PSDCA was not evident in the study. Historical suggestions that these tumors exhibit moderate radiation sensitivity were supported by survival analysis, underscoring surgical intervention as the primary curative avenue for PSDCA. Adjuvant radiochemotherapy could be considered in cases with poor prognostic markers or for palliative purposes, while neoadjuvant therapy’s potential impact requires further exploration.
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