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Wilms Tumor Survival Analysis In Kenya

Saturday, October 20, 2012: 2:38 PM
Versailles Ballroom (Hilton Riverside)
Jason R. Axt, MD1, Fatmah K. Abdallah2, Meridith D. Axt3, Jessie N. Githang'a2, Erik N. Hansen4, Joel Lessan5, Julius Kyambi, Honorary, member, of, Surgical, Section, of, AAP5, James M. Ndung'u5, Mark Newton6, Festus Njuguna7, Ancent Nzioka8, Joyce Musimbi7, Michael Mwachiro9, Oliver V. Oruko2, Kirtika T. Patel10, Robert K. Tenge11, Russell E. White9, James A. O'Neill Jr.1 and Harold N. Lovvorn III, MD, FACS, FAAP12, (1)Department of Pediatric Surgery, Vanderbilt University Medical Center, Nashville, TN, (2)Department of Human Pathology, University of Nairobi, Nairobi, Kenya, (3)Pediatric Intensive Care, Vanderbilt University Children's Hospital, Nashville, TN, (4)Department of Pediatric Surgery, Kijabe Hospital, Kijabe, Kenya, (5)Department of Pediatric Surgery, University of Nairobi, Nairobi, Kenya, (6)Department of Anesthesia, Kijabe Hospital, Kijabe, Kenya, (7)AMPATH Oncology Programme, Moi Teaching and Referral Hospital, Eldoret, Kenya, (8)Department of Pathology, Kijabe Hospital, Kijabe, Kenya, (9)Department of General Surgery, Tenwek Hospital, Bomet, Kenya, (10)Department Of Immunology, Moi University, Eldoret, Kenya, (11)Department of Pediatric Surgery, Moi University, Eldoret, Kenya, (12)Department of Pediatric Surgery, Monroe Carell Jr. Children's Hospital at Vanderbilt, Nashville, TN

Purpose:   Survival from Wilms Tumor (WT) exceeds 90% at 5 years in developed nations, whereas 2-year event-free survival in Kenya reached only 35% at last report in 2001.  Much of this disparity has been attributed to environmental and clinical factors associated with resource limitations but may also reflect unique intrinsic cancer biology. To clarify factors linked to these poor outcomes, Kenyan and American investigators established a comprehensive Kenyan WT registry, comprised of patients from the two academic medical institutions and the two largest missionary hospitals in this developing country.

Methods:   WT patients diagnosed between January 2008 and January 2012 at these four institutions were identified. Files were abstracted for demographic characteristics, treatment regimens, and enrollment in the National Hospital Insurance Fund (NHIF).  Children under 15 years of age having imaging reflective of primary kidney tumor, fine needle aspiration or tissue biopsy consistent with WT were included. 

Results:   A total of 133 WT patients were identified for the study period. Minimum staging was estimated using Children's Oncology Group criteria and was available for 125 patients: 4 (3.2%) stage 1, 53 (42.4%) stage 2, 45 (36%) stage 3, 21 (16.8%) stage 4, and 2 (1.6%) stage 5.  Mean age at diagnosis was 41 months (95% CI 36.7 – 45.3). Loss to follow up (LTFU) was 49.5%. Two-year event-free survival (EFS) was 55% for all patients.  Among the 30 patients who completed all therapy, 2-year EFS was 96% (Figure).  Cox proportional hazard of death was 0.039 for those who completed therapy (p = 0.001) and 0.145 for those enrolled in NHIF (p<0.001).  Patients enrolled in NHIF tended to complete more or all therapy (Table; Fishers exact, p = 0.001).   In-treatment death and abandonment of care was common (Table).

Totals

Highest Level of Treatment Completed

No Therapy Started

Preoperative Chemotherapy

Resection

Postoperative Chemotherapy

Radiation

Completed All Therapy

NHIF Insurance

No:       46 (51.1%)

23 (50)

3 (6.5)

7 (15.2)

1 (2.2)

2 (4.4)

10 (21.7)

Yes:     44 (48.9%)

5 (11.4)

2 (40)

16 (36)

3 (6.8)

3 (6.8)

15 (34.1)

Follow Up Status

Dead:   37 (38.1%)

20 (54)

3 (8.1)

10 (27)

2 (5.4)

1 (2.7)

1 (2.7)

Alive:   12 (12.4%)

2 (16.7)

0 (0)

1 (8.3)

0 (0)

0 (0)

9 (75)

LTFU:  48 (49.5%)

6 (12.5)

3 (6.3)

16 (33.3)

3 (6.3)

4 (8.3)

16 (33.3)

Conclusion:   Analysis of a new Kenyan WT registry shows that survival has increased marginally since last report, although patients who complete all levels of therapy show 2-year survival approaching western standards. Efforts should be made to enhance compliance with treatment protocols with interventions such as NHIF enrollment. However, Kenyan WT patients experience a high in-therapy death rate, which may represent treatment-resistant disease or susceptibility to treatment toxicity.