Rhabdomyosarcoma: Pediatric Prognostic Variability Among Embryonal and Alveolar Histological Subtypes
Aug 13, 2024
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Arjan Bhamra, Miana Campbell, S.Abishag Heresh, Maria Mihai, Kianna Yasis, & Hana Zubair
Pediatric Cancer Research & Internship Program
Abstract
Rhabdomyosarcoma, in the context of paediatric cancer, has two main subtypes; embryonic and alveolar. These types of cancer are both well-known by paediatric oncologists and cancer treatment researchers, however they have highly varying fatality rates, treatment efficacies, and alveolar patients and families often require additional support. This paper investigates the main differences in embryonic and alveolar rhabdomyosarcoma, highlighting the difference in survival rates, as well as related medical professions, diagnosis, treatment options, and the impacts resulting from this difference.
Introduction
Rhabdomyosarcoma is a form of cancer that originates in the soft tissues, such as the skeletal muscles, affecting mainly children and adolescents. This cancer is classified into two subtypes: alveolar and embryonal. These subtypes vary in prognosis and biological conditions. Embryonal rhabdomyosarcoma tends to be more common, as it arises from cells that resemble the early stages of muscle development and is more likely to occur in younger children. There is also a correlation to genetic mutations that lead to abnormal growth in muscle precursor cells. On the other hand, Alveolar rhabdomyosarcoma is associated with specific genetic translocations that are less common and often linked to more aggressive tumor behavior. The distinct genetic pathways that lead to ERMS are thought to be more frequently activated or altered during early development, which might explain why ERMS is seen more often in clinical practice.
Diagnosis
Rhabdomyosarcoma (RMS) in pediatrics is frequently first noticed during physical exams, as the malignant tumor originating from skeletal muscle progenitors leads to visibility of clinical signs and symptoms dependent on its subtype and location. Specifically, Alveolar RMS often manifests in the extremities, trunk, or perineal region, typically presenting as a rapidly growing, firm mass. On the other hand, Embryonal RMS is more frequently found in the head and neck area, genitourinary tract, or retroperitoneum, and may cause localized swelling, pain, or functional impairment in the affected area.
Diagnostic evaluation of RMS involves a combination of imaging studies, such as magnetic resonance imaging (MRI) or computed tomography (CT) scans, to assess the tumor’s size, location, and potential involvement of adjacent structures. Ultrasound may also be used, particularly for tumors in the head and neck or genitourinary regions. Histopathological examination, following a biopsy, is essential for differentiating between Alveolar and Embryonal subtypes. Additionally, immunohistochemical staining and genetic testing, such as fluorescence in situ hybridization (FISH) or reverse transcription-polymerase chain reaction (RT-PCR), can identify specific chromosomal translocations, aiding in the accurate classification of the tumor and guiding prognostic assessments.
The signs and symptoms at presentation, alongside these diagnostic tools, play a crucial role in determining the treatment plan and prognosis for patients with Alveolar or Embryonal RMS. Understanding the clinical manifestations and appropriate use of medical equipment is essential for early detection and effective management of this aggressive malignancy.
Medical Professions
As RMS is rare and can be complex to treat, it only makes sense that those treating it would have to be trained individuals who have experience with RMS. Medical professionals you’d typically see on a treatment team for pediatric patients with RMS include a pediatric oncologist, a pediatric orthopedic surgeon, a radiation oncologist, a pathologist, a pediatric hematologist, and a pediatric physiatrist.
Pediatric Oncologist:
Schooling: Bachelor’s degree, medical degree, pediatric residency, pediatric oncology fellowship, board certification from the American Board of Pediatrics, and a subboard certification for pediatric hematology/oncology.
Salary:
Base pay: $181K-$338K/yr.
Additional pay: $73K-$136K/yr.
Total pay range: $254K-$474K/yr.
Median total pay: $339k/yr.
Role: A pediatric oncologist will be the one to oversee the treatment of the child with RMS, creating treatment plans dependent on the child’s need and the tumor’s location, size, and type.
Pediatric Orthopedic Surgeon:
Schooling: Bachelor’s degree, medical degree, orthopedic surgery residency, subspecialty training in pediatric orthopedics and/or pediatric spinal deformity (typically taking one year), board certification from the American Board of Pediatrics, and board certification from the American Board of Orthopedic Surgery.
Salary:
Base pay: $193K-$359K/yr.
Additional pay: $125K-$233K/yr.
Total pay range: $318K-$593K/yr.
Median total pay: $423K/yr.
Role: A pediatric orthopedic surgeon will perform surgery on the child to remove the tumor and restore function at the site of the tumor.
Radiation Oncologist:
Schooling: Bachelor’s degree, medical degree, one year of clinical training in internal medicine or surgery, radiation oncology, residency, and a certification from the American Board of Radiology.
Salary:
Base pay: $95K-$172K/yr.
Additional pay: $76K-$141K/yr.
Total pay range: $170K-$313K/yr.
Median total pay: $227K/yr.
Role: A radiation oncologist will use radiation therapy to treat RMS in the patient.
Pathologist:
Schooling: Bachelor’s degree, medical degree, pathology residency, certification from the American Board of Pathology.
Salary:
Base pay: $135K-$252K/yr.
Additional pay: $56K-$104K/yr.
Total pay range: $190K-$355K/yr.
Median total pay: $254K/yr.
Role: A pathologist will analyze tissue samples and examine the tumor from the child to confirm an RMS diagnosis.
Pediatric Hematologist:
Schooling: Bachelor’s degree, medical degree, pediatric residency, pediatric hematology/oncology fellowship, board certification from the American Board of Pediatrics, and a subboard certification for pediatric hematology/oncology.
Salary:
Base pay: $224K-$417K/yr.
Additional pay: $168K-$314K/yr.
Total pay range: $329K-$731K/yr.
Median total pay: $522K/yr.
Role: A pediatric hematologist will perform tests to see if the RMS in the child has spread to bone marrow.
Pediatric Physiatrist:
Schooling: Bachelor’s degree, medical degree, physiatrist residency, pediatric fellowship, and board certification from the American Board of Pediatrics.
Salary:
Base pay: $183K-$331K/yr.
Additional pay: $46K-$87K/yr.
Total pay range: $229K-$418K/yr.
Median total pay: $305K/yr.
Role: A pediatric physiatrist will help to rehabilitate the child after their treatment for RMS is done.
Treatments
Radiation therapy, chemotherapy, and surgery are the main forms of treatment. Each of these approaches is tailored to the specific characteristics and location of the tumor, providing a comprehensive strategy to combat the disease. New advancements in treatment techniques are continuously improving the effectiveness and precision of these therapies. Combining these methods often leads to better overall outcomes and a more personalized treatment plan for patients.
Surgery: When the specific position and size of a tumor are known, doctors will typically proceed with surgery as the first measure to ensure precise and full recession.
Chemotherapy: Chemo plays a vital role in treating RMS, especially when the tumor is located close to important anatomical areas or organs that are essential for normal bodily functions, which is most often the case. Chemotherapy reduces the likelihood of metastases and raises survival chances.
Radiation Therapy: Radiation therapy is used in addition to chemotherapy and surgery, especially in cases where total surgical excision is not feasible. Thanks to advancements in radiation treatments, damage to healthy tissue can be minimized by precise targeting.
Potential treatments known as "targeted therapies" are beginning to emerge; this form of therapy targets immune responses and biochemical pathways connected to RMS. Clinical trials indicate potential for these methods, despite their generally experimental nature. To further advance these promising treatments, increased support for research and clinical trials is crucial. By investing in these areas, we can accelerate the development of more effective therapies and improve patient outcomes.
Statistics
Rhabdomyosarcoma (RMS) is one of the rarer cancers, being only 3% of pediatric cancer cases, with 50% of RMS cases being in kids younger than 10 years old. Specifically comparing embryonal rhabdomyosarcoma (ERMS) with alveolar rhabdomyosarcoma (ARMS), however, there are statistically some key differences between the two.
ERMS is the most common type of RMS, accounting for 60% of RMS cases. ARMS is the 2nd most common type of RMS, although it only accounts for 20% of RMS cases. For children aged 1-4, the 5-year survival rate for ERMS is 77%, but for infants and adolescents, that number drastically drops down to 47% and 48%. The survival rate for children with ARMS, however, depends less on age and more on the risk group.
Children in the intermediate-risk group have a 50-70% survival rate, whereas children in the high-risk group only have a 20-30% survival rate.
The overall 5-year survival rate for ERMS is an estimated 81%, and the overall 5-year survival rate for ARMS is 68%, giving ERMS a 13% higher 5-year survival rate than ARMS.
Impacts
Our statistics have highlighted the typically higher survival rates associated with embryonal rhabdomyosarcoma compared to alveolar rhabdomyosarcoma. It is critical to understand the differences in these two subtypes, as this is essential for tailoring medical approaches in paediatric cancer. The impact of this conclusion is noted across various fields, particularly clinical decision making, patient and family support, future research, and policy and healthcare system impacts.
When prompted with separate cases of embryonal and alveolar subtypes, oncologists may choose to undertake more aggressive treatments and to consider experimental therapies much quicker given the poor prognosis for alveolar subtype. However, it is imperative to raise awareness prior so that these systemic adjustments can be made. These prognostic differences may also positively contribute to improving risk stratification and personalized medical treatment in clinical settings.
The impacts of raising awareness to survival rate variations depending on the subtype of rhabdomyosarcoma can also be felt in the realm of patient and family support. It is imperative to communicate the difference in survival rates so that the patient and family are not left to interpret the information available on the internet. This also means that families with the more aggressive form of rhabdomyosarcoma may need higher levels of counseling supports, financial assistance, etc., which is valuable information for their providers and insurers.
Additionally, when this difference is highlighted in scientific circles, researchers can begin to shift their focus into the more pertinent and urgent field, or particularly the ones with higher fatality and lower recovery rates. Alveolar rhabdomyosarcoma patients may be prioritized for clinical trials and treatments in order to improve future treatment efficacy and survival outcomes.
Lastly, understanding these prognostic differences will likely influence policy and healthcare funding, i.e., research funding for the more aggressive alveolar rhabdomyosarcoma. It is important to recognize that insurance policies may need to shift to allocate better coverage for alveolar patients due to their need for increased treatment and support. In order to truly begin to resolve the gap in survival rates, systemic changes must occur to give both the doctor and the patient the highest chance of success.
Conclusion
Ultimately, the differences between embryonal and alveolar rhabdomyosarcoma hold crucial consideration in terms of clinical approaches. The distinct survival rates and treatment challenges associated with each subtype underscore the need for tailored medical strategies, particularly for the more aggressive alveolar variant. By raising awareness of these disparities, healthcare providers can ensure that patients and their families receive appropriate support and that research efforts are directed toward improving outcomes for those at higher risk. Moreover, recognizing these differences can inform policy and funding decisions, leading to more effective and equitable care for all pediatric patients with rhabdomyosarcoma.
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