Introduction:
Bone sarcomas inclusive of osteosarcoma (OGS) and Ewing’s sarcoma (ES)
are rare, aggressive yet chemosensitive tumors with variable survival
rates in Low and Middle-Income Countries (LMIC). There are various
factors including delayed presentation with advanced disease and higher
rates of metastatic disease, inadvertent prior treatment by primary care
physicians, high dropout rates and poor adherence due to socioeconomic
constraints with resultant compromised outcomes.
Non-High-Dose-Methotrexate (Non-HDMTX) based regimens for osteosarcoma
have gained popularity in these regions due to ease of administration on
daycare basis, low cost and convenience. Therefore, finding valuable
prognostic factors specifically targeting LMIC is crucial for predicting
high-risk patients and early intervention to improve survival rates.
Among patients with osteosarcoma, possible prognostic factors, tumor
size, metastatic disease at the time of diagnosis, histological grade,
histologic response to neoadjuvant chemotherapy (NACT), and adequate
surgical margins have consistently shown a strong correlation with
survival. [1-2] Non-uniformity of chemotherapy protocols for
osteosarcoma preclude generalisability of results. We have previously
published our experience with our institutional standard low cost,
non-HDMTX based “OGS-12” protocol where serum alkaline phosphatase
level for EFS and performance status for OS were found to be independent
prognosticators, concordant with other reports, including those from
India [3-6]. Histological response to NACT was an independent
predictor of both EFS and OS which is also well-established.
For Ewing’s sarcoma, multiple prognostic factors have been reported,
such as age, gender, localization, volume and size of the primary tumor,
presence of metastasis, treatment regimens, a baseline level of
hemoglobin or lactate dehydrogenase, and pathologic response to
neoadjuvant chemotherapy [7-9]. In our published data on patients
with Ewing’s sarcoma at our institute treated with the “EFT-2001”
protocol, statistically significant prognostic factors included longer
symptom duration, >= 99% necrosis, and protocol
completion. [10]
There are unique challenges with rare cancers like bone sarcomas
globally and a prognostic model with wide applicability including for
the patients in LMIC wherein including social challenges also play a
role is an unmet need. Special challenges in LMIC include lack of
awareness among patients and primary health care providers with
resultant delayed presentation, upstaging and high tumor burden.
We have aimed to identify prognostic factors including those specific to
LMIC. Additionally, we have derived and validated a prognostic score for
osteosarcoma that integrates biologic and social factors and is tailored
for patients from an LMIC setting using a non-HDMTX-based protocol.