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Nephroblastoma, or Wilms tumor, is the most common malignant kidney tumor in children, accounting for 5 to 10% of pediatric cancers [1]. In developed countries, survival rates exceed 90% thanks to multimodal treatment protocols established by the International Society of Pediatric Oncology (SIOP) and the National Wilms Tumor Study Group (NWTSG) [2, 3]. In sub-Saharan Africa, the management of this disease faces specific challenges related to diagnostic delays, socio-economic constraints, and limited access to specialized care [4, 5]. The Franco-African Pediatric Oncology Group (GFAOP) has initiated the adaptation of SIOP protocols to the African context, demonstrating their feasibility and effectiveness [6, 7]. Our study aims to evaluate the experience of the Thiès Regional Hospital Center in the management of nephroblastoma by analyzing epidemiological, therapeutic, and prognostic aspects in a decentralized healthcare context similar to the challenges reported in other developing countries [8].

This is an observational, retrospective, cross-sectional, descriptive, and analytical study conducted in the pediatric surgery department of the Thiès Regional Hospital Center over an 18-month period, from September 1, 2022, to March 1, 2024. Forty-two patients aged 0 to 15 years with a confirmed diagnosis of nephroblastoma were included and treated according to the SIOP 2001 protocol adapted by the GFAOP [9]. All patients had a diagnosis of nephroblastoma based on imaging (ultrasound/CT scan) with their cases discussed in multidisciplinary team meetings. Statistical analyses were performed using R software version 4.3.1. Quantitative variables were described by their mean (± standard deviation) or median depending on the distribution [Figure1, 2]. Qualitative variables were described by their numbers and percentages. For univariate analysis, event-free survival (EFS) was defined as the time between diagnosis and the occurrence of an event (recurrence, metastasis, or death). Overall survival (OS) was defined as the time between diagnosis and death from any cause. Survival curves were estimated using the Kaplan-Meier method and compared using the log-rank test [10]. For categorical prognostic factors, crude hazard ratios (HR) with their 95% confidence intervals (95% CI) were calculated using univariate Cox models [11].

Figure 1: Distribution by age group.

Figure 2: Distribution according to SIOP stage.

Over the 18-month study period, retrospective analysis of the records allowed us to include 42 patients who met the selection criteria, representing an average incidence of 2.3 cases per month in our center. Descriptive analysis of the cohort revealed that the median age was 3 years (mean 3 years and 10 months, range: 9 months to 14 years). The age distribution showed a predominance of the 1-4 age group (52.4%, n=22). The sex ratio (M/F) was 0.75. Assessment of socioeconomic status, based on the parents' occupation, indicated that the majority of patients (61.9%, n=26) came from low-income households. Analysis of the reasons for consultation showed that all patients (100%, n=42) had a palpable abdominal mass at diagnosis. The most frequently reported associated signs in the records were abdominal pain (52.4%, n=22) and hematuria (7.1%, n=3). No cases were discovered incidentally. Ultrasound and computed tomography (CT) scans, performed in 90.5% and 100% of patients, respectively, revealed an average tumor volume of 150.2x124.2x85.4 mm, or 720 ml, with extremes of 55x56x53 mm, or 15 ml, and 264x205x157 mm, or 3500 ml, at diagnosis. The initial staging allowed 26 patients (61.9%) to be classified as localized and 16 patients (38.1%) as metastatic or advanced. Review of treatment protocols confirmed that almost all patients (97.6%, n=41) had received preoperative chemotherapy according to the GFAOP protocol. All patients underwent surgery, with an average operation time of 1 hour 40 minutes. The main surgical procedure was extended nephrectomy (88.1%, n=37). Pathological analysis of the surgical specimens classified the majority of tumors as intermediate risk (78.6%, n=33) according to the SIOP classification [12]. The distribution by histological stage showed a predominance of stage II (44%, n=18). With a follow-up period of 6 months after surgery, analysis of the records showed a simple progression in 21 patients (50%), a recurrence or metastasis rate of 11.9% (n=5), and an overall mortality rate of 26.2% (n=11). The analysis also highlighted challenges in continuity of care, with a treatment discontinuation rate of 11.9% (n=5) and documented compliance issues in 30.9% (n=13) of patients. The univariate analysis identified several factors significantly associated with poorer overall survival [Table 1]. These include advanced stage (III/IV): HR = 4.12, p=0.01, high histological risk group: HR = 3.89, p=0.02, presence of metastases at diagnosis: HR = 5.83, p<0.01, and poor treatment compliance: HR = 5.01, p<0.01. Tumor volume ≥ 720 ml showed a trend toward significance (p=0.06).

Table 1: Univariate analysis of factors associated with overall survival.

Our study, with its retrospective observational design, provides an overview of the management of nephroblastoma in a regional hospital in sub-Saharan Africa. The results described highlight epidemiological, therapeutic, and prognostic realities that differ from those observed in high-income countries, while confirming the feasibility of a protocolized approach [13, 14]. The predominance of the 1-4 age group in our cohort (52.4%) is consistent with data in the literature [15]. However, the almost systematic presence of a palpable abdominal mass (100% of cases) and the large average tumor volume (720 ml) at diagnosis are strong indicators of late diagnosis. In developed countries, a significant number of tumors are discovered incidentally during examinations for other reasons [16]. The absence of such cases in our series, combined with the high proportion of patients from disadvantaged socioeconomic backgrounds (61.9%), suggests that barriers to healthcare access and failure to seek early consultation delay diagnosis. This initial delay has a direct prognostic implication, as evidenced by the significant proportion (38.1%) of metastatic or locally advanced forms at diagnosis. The implementation of the SIOP 2001 protocol adapted by the GFAOP was possible for 97.6% of our patients, which is a remarkable result. Analysis of surgical and pathological reports shows that surgery and histological classification can be performed according to international standards, with a distribution of stages and histological types (predominantly stage II and intermediate risk) comparable to that of other series using preoperative chemotherapy [17]. However, our descriptive study highlights the limitations of this feasibility. The average delay of 15 days between the end of chemotherapy and surgery, with extremes of up to 30 days, illustrates the organizational constraints. More significantly, problems with treatment compliance (30.9%) and dropouts (11.9%) highlight the socioeconomic vulnerability of the cohort, which is a critical obstacle to the effectiveness of treatment, however standardized it may be. The overall mortality rate of 26.2% and recurrence rate of 11.9% in our series are substantially higher than the survival rates exceeding 90% reported in Europe and North America [2, 3]. This difference cannot be attributed solely to tumor biology, given the predominance of tumors with a good prognosis (intermediate risk). Cross-sectional analysis of our cohort shows that advanced stage at diagnosis is a major prognostic factor. Intraoperative complications (tumor breach, severe adhesions), although uncommon, are more likely to occur in large tumors and may influence the risk of local recurrence [18]. Socioeconomic vulnerability is the cross-sectional factor that potentially impacts all stages: delayed diagnosis, poor treatment tolerance, compliance issues, and follow-up difficulties [19]. The occurrence of deaths during surgery (1 case) and in intensive care (2 cases) also highlights the challenges of managing complications in a resource-limited environment [20]. The main strength of this study is that it provides real-world data from a secondary care center, a crucial level of care for accessibility in Africa. The major limitation is inherent in its retrospective design, with the potential selection and information biases that this entails (missing data, uneven follow-up). The limited sample size and short follow-up period (6 months) do not allow for robust multivariate statistical analyses or the evaluation of long-term survival. The experience of the Thiès Regional Hospital Center demonstrates the importance of decentralizing specialized pediatric oncology care in Africa, making treatment more accessible to rural populations [20, 21].

This descriptive study confirms that the application of adapted SIOP protocols is operational in African regional hospitals. It clearly identifies the levers for improving prognosis, which lie not only in medical expertise, but also in a comprehensive approach that includes strengthening health systems for earlier diagnosis, deploying socio-economic support to improve compliance and reduce dropouts, and finally, continuing training and technical support for local multidisciplinary teams. Prospective studies with longer-term follow-up are needed to clarify the prognostic factors specific to the African context.

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