Introduction
Since the initial attempts to treat children with renal cancer over 50
years ago, outcome for children with renal cancer has generally become
promising. While the first endeavors mainly included surgical treatment,
in the early 60s radiotherapy and chemotherapy were introduced, leading
to cure of patients, including some with metastatic disease. (1) Since
then, overall survival rates for the most common type of renal tumors in
childhood (nephroblastoma or Wilms tumor) have improved to more than 90
percent. These excellent treatment outcomes are similar in the 2 largest
clinical trial groups (the Children’s Oncology Group Renal Tumor
Committee (COG-RTC; former National Wilms Tumor Study Group (NTWSG)),
and the International Society of Pediatric Oncology Renal Tumor Study
Group (SIOP-RTSG). Despite the difference in upfront treatment choice
(primary surgery when feasible (COG-RTC) or preoperative chemotherapy
(SIOP-RTSG)) both groups have optimized the stratification of patients
in their trials by modifying the intensity of treatment according to
individual risk factors, in order to improve outcome for high-risk renal
tumor types, but also to reduce early and late toxicity in lower and
intermediate risk tumors as much as possible. (2-4)
This improvement in risk stratification has resulted in better outcomes
and less cancer related toxicity. However, for remaining small subgroups
of pediatric renal tumor patients, with very poor outcomes, further
understanding of the underlying biology, in correlation with
clinic-pathological characteristics, is an unmet need. Further, standard
multidisciplinary treatment (surgery, radiotherapy, chemotherapy) can be
challenging to access and/or deliver in some low and middle income
countries (LMIC). The power inherent in international collaboration to
address these challenges was a driving principle that supported the
creation of the HARMONICA (HARMONIzation and COllaboration) initiative
in 2015, when we established an organized collaborative structure for
transatlantic experts from COG-RTC and SIOP-RTSG. The mandate of
HARMONICA is to identify specific challenges for pediatric renal tumor
subsets in order to meet the aims of our global approach to cure every
child with a renal tumor with limited toxicity.
The HARMONICA group meets at least once a month by videoconferences, and
as much as possible also face to face, at least once or twice a year,
during existing pediatric cancer conferences. In addition, several
transatlantic HARMONICA expert subgroups are collaborating on specific
topics. All work is currently done by a tremendous engagement of many
enthusiastic members of both study groups. Despite the fact of obvious
advantages, HARMONICA is still lacking funding and needs to optimize
their structure as a legal entity. Notwithstanding such limitations, in
this special issue of PBC, we present the achievements, the challenges,
and the future perspectives, identified by these expert groups.