Desmoplastic small round cell tumour (DSRCT) is an extremely rare and aggressive type of cancer that typically develops in the abdomen and pelvis, most commonly affecting young males. Treatment combines multiple approaches, including surgery, chemotherapy, and radiation therapy, aiming to remove tumours, slow disease progression, and improve quality of life. Because this cancer is so uncommon, there is no universally agreed treatment standard, but medical teams use established methods alongside ongoing research into newer therapies to give patients the best possible outcomes.

How Treatment Decisions Are Made for This Rare Cancer

When someone receives a diagnosis of desmoplastic small round cell tumour, the medical team faces a unique challenge. This cancer is so rare that only about 200 cases have been recorded worldwide since doctors first identified it in 1989. Because there are so few patients, researchers have limited information to guide treatment decisions compared to more common cancers.^[1]

The treatment approach depends heavily on where the tumours are located, how large they have grown, whether the cancer has spread to other parts of the body, and the patient’s overall health. Most people diagnosed with DSRCT are young males between ages 10 and 30, though anyone can develop this condition.^[3] The tumours usually form multiple growths in the peritoneum—the membrane lining the inside of the abdomen and pelvis—and they can spread quickly to nearby organs such as the bladder, colon, and liver.^[2]

Currently, there is no single standard treatment pathway that all doctors follow, precisely because DSRCT is so rare. Instead, medical teams typically recommend a combination of treatments tailored to each patient’s situation. The main goals are to remove as much of the cancer as possible through surgery, use chemotherapy drugs to kill cancer cells throughout the body, and apply radiation therapy to destroy remaining tumour cells. Even with aggressive treatment, this cancer often returns, requiring patients to undergo additional rounds of therapy.^[1]

Because standard treatments don’t always achieve lasting remission, many patients and their doctors consider participation in clinical trials. These research studies test new drugs and treatment methods that might offer better outcomes than current options. Clinical trials are particularly important for rare cancers like DSRCT, where every patient’s experience contributes valuable knowledge to the medical community.

Standard Treatment Approaches

Surgery to Remove Tumours

Surgery plays a central role in treating desmoplastic small round cell tumours. The surgeon’s goal is to remove all visible cancer, which often means taking out multiple tumours scattered throughout the abdominal cavity. This type of extensive surgery is called cytoreductive surgery, meaning the surgeon works to reduce the amount of cancer in the body as much as possible.^[9]

The challenge with DSRCT is that the tumours often grow in and around vital organs, making complete removal difficult or impossible. In many cases, there are dozens to hundreds of small tumours coating the inside surface of the abdomen. One very large dominant mass typically appears in the omentum—a layer of fatty tissue covering the intestines—along with additional large clusters in the pelvis and along the right side of the abdomen.^[9]

When tumours have grown too large or are wrapped around critical organs, doctors may recommend chemotherapy first to shrink the cancer before attempting surgery. This approach, called neoadjuvant chemotherapy, can make the tumours easier to remove and increase the chances of a successful operation.^[20] After chemotherapy has reduced the tumour size, surgeons can perform a more thorough removal with less risk to surrounding organs.

If the surgical team cannot remove all cancer cells—which happens in most cases—the disease is likely to return. Even microscopic amounts of remaining cancer can grow back in the same location or spread to distant parts of the body. This is why surgery is almost always combined with other treatments rather than being used alone.^[1]

Chemotherapy

Chemotherapy uses powerful drugs to kill cancer cells throughout the body. Because DSRCT often involves multiple tumours and has a high risk of spreading, chemotherapy is a crucial part of treatment for nearly all patients. Doctors typically use chemotherapy before surgery, after surgery, or both.^[1]

The most commonly used chemotherapy approach for DSRCT is called the P6 regimen. This treatment protocol was developed specifically for this type of cancer and combines multiple chemotherapy drugs given in cycles. The P6 regimen includes drugs that target cancer cells in different ways, making the treatment more effective than using a single drug alone.^[10]

Some medical centres use an approach called interval-compressed chemotherapy, which means giving the drugs on a more frequent schedule with shorter breaks between treatment cycles. This method aims to keep constant pressure on the cancer cells, giving them less time to recover and grow between treatments.^[17]

Chemotherapy for DSRCT typically continues for several months. The exact duration depends on how well the tumours respond to treatment and how well the patient tolerates the drugs. Doctors monitor progress through regular imaging scans to see if the tumours are shrinking and blood tests to check how the body is handling the medication.

Common side effects of chemotherapy include fatigue, nausea and vomiting, diarrhoea, and increased risk of infection because the drugs affect the bone marrow’s ability to make blood cells. Hair loss is also common with many chemotherapy drugs. Most side effects are temporary and improve after treatment ends, though some patients experience longer-lasting effects.^[3] Medical teams provide supportive care to help manage these side effects, including anti-nausea medications, antibiotics if infections develop, and other treatments to maintain quality of life during chemotherapy.

Hyperthermic Intraperitoneal Chemotherapy (HIPEC)

A specialized treatment called hyperthermic intraperitoneal chemotherapy, or HIPEC, has become an important option for DSRCT. This procedure combines surgery with heated chemotherapy delivered directly into the abdominal cavity. After the surgeon removes as many visible tumours as possible, a warm chemotherapy solution is circulated throughout the abdomen for about two hours.^[1]

The heat helps the chemotherapy drugs penetrate more deeply into tissues where microscopic cancer cells might remain. Because the chemotherapy is delivered directly to the abdomen rather than through the bloodstream, very high concentrations can be used without exposing the entire body to these powerful drugs. This approach targets any remaining cancer cells in the peritoneum while minimizing side effects to other parts of the body.^[3]

Research has shown that patients who receive HIPEC along with surgery and standard chemotherapy tend to have better survival rates than those who receive surgery and chemotherapy alone. The combination of aggressive surgical removal, heated chemotherapy washing the abdominal cavity, and systemic chemotherapy before and after surgery gives patients the most comprehensive attack on the cancer.^[9]

HIPEC is a complex procedure that requires a specialized surgical team and extended operating room time. Not all hospitals offer this treatment, so patients may need to travel to major cancer centres with expertise in treating DSRCT. Recovery after HIPEC can take longer than recovery from surgery alone because the procedure is more extensive.

Radiation Therapy

Radiation therapy uses high-energy beams to kill cancer cells. For DSRCT, radiation can be delivered from outside the body using a machine that aims beams at the tumours, or from inside the body by placing radioactive materials near the cancer.^[1]

One approach is whole abdomen radiotherapy (WART), which treats the entire abdominal cavity where DSRCT tumours typically spread. This can be given after chemotherapy to destroy any remaining cancer cells that weren’t removed by surgery. However, radiating such a large area can cause significant side effects, including damage to the intestines, kidneys, liver, and other organs within the treatment field.^[10]

A newer technique called whole abdominopelvic intensity-modulated radiation therapy (WAP-IMRT) offers a more precise way to deliver radiation. This method uses computer-controlled machines to shape the radiation beams, allowing higher doses to tumours while reducing exposure to surrounding healthy tissues. Studies suggest WAP-IMRT causes less radiation toxicity compared to conventional WART, though it is still a complex treatment that requires careful planning.^[10]

Some patients receive radiation therapy before surgery to shrink tumours and make them easier to remove. Others receive it after surgery to kill cancer cells that might remain. The timing depends on the individual treatment plan developed by the medical team. In some cases, doctors may recommend a specialized form of radiation called proton therapy, which can target tumours more precisely while avoiding nearby organs. However, proton therapy is only available at a limited number of centres.^[6]

Common side effects from abdominal radiation include diarrhoea, fatigue, nausea, and skin irritation in the treatment area. These effects typically develop gradually during the course of treatment and may continue for some weeks after radiation ends. Long-term effects can include scarring of tissues within the radiation field and increased risk of damage to organs that received radiation exposure.^[3]

Innovative Treatments Being Tested in Clinical Trials

Understanding Clinical Trial Phases

Before discussing specific experimental treatments, it’s helpful to understand how clinical trials work. New drugs and therapies go through three main phases of testing. Phase I trials focus on safety, determining what dose can be given without causing severe side effects. These trials typically involve small numbers of patients. Phase II trials test whether the treatment actually works against the cancer, looking for signs that tumours shrink or stop growing. Phase III trials compare the new treatment to the current standard treatment to see if the new approach is better, equal, or worse. Each phase builds on knowledge from the previous one.

Targeted Therapies and Molecular Approaches

Researchers have identified that DSRCT is caused by a specific genetic abnormality. In this cancer, parts of two chromosomes break apart and rejoin incorrectly, creating an abnormal fusion of the EWS gene and the WT1 gene. This EWS-WT1 fusion protein drives the cancer’s growth by affecting how cells regulate their genes.^[1] Understanding this molecular cause has opened new avenues for treatment development.

Scientists are working on drugs that specifically target the proteins and pathways controlled by the EWS-WT1 fusion. The fusion protein influences several important growth signals, including receptors for epidermal growth factor (EGFR), insulin-like growth factor (IGF-1), and platelet-derived growth factor (PDGFA). Drugs that block these growth signals are being studied in clinical trials for DSRCT patients.^[10]

One promising experimental drug is ONC-201, a novel chemotherapeutic agent that has shown the ability to inhibit tumour growth in preclinical laboratory models of DSRCT. This drug works differently from traditional chemotherapy by targeting specific pathways that cancer cells use to survive. Early studies suggest it may be effective against DSRCT, and clinical trials are ongoing to test its safety and efficacy in patients.^[10]

CDK4/6 inhibitors represent another class of targeted drugs being investigated. These medications block proteins called cyclin-dependent kinases that help control cell division. By preventing cancer cells from dividing, CDK4/6 inhibitors can slow tumour growth. Several of these drugs are already approved for other types of cancer and are now being tested in DSRCT patients.^[10]

Another experimental approach involves tyrosine kinase inhibitors. These drugs block enzymes that cancer cells use to send growth signals. One such drug, anlotinib, has been tested in patients with DSRCT and other sarcomas. Studies have shown varying levels of effectiveness, with some patients experiencing tumour shrinkage or stabilization of their disease.^[10]

Immunotherapy Approaches

Immunotherapy works by helping the patient’s own immune system recognize and attack cancer cells. This approach has revolutionized treatment for many types of cancer, and researchers are now exploring whether it can help DSRCT patients. Because this disease primarily affects young people, immunotherapy is particularly appealing because it tends to have fewer long-term side effects compared to traditional chemotherapy or radiation.^[10]

Several proteins on the surface of DSRCT cells make them potential targets for immunotherapy. One such protein is B7-H3, which appears in high levels on DSRCT tumours. Researchers are developing antibodies that attach to B7-H3 and either mark the cancer cells for destruction by the immune system or deliver toxic drugs directly to the tumour. This type of treatment is called an antibody-drug conjugate.^[10]

Another target is GD2, a molecule found on the surface of DSRCT cells. Antibodies against GD2 are already used to treat other types of cancer and are being studied in DSRCT. Similarly, researchers are investigating antibodies that target HER2, another protein that appears on some DSRCT tumours.^[10]

Some scientists have noticed that DSRCT cells express receptors for male hormones called androgen receptors. This finding has led to trials testing whether drugs that block these receptors—similar to treatments used for prostate cancer—might help slow DSRCT growth. While still early in development, this represents an interesting new direction for research.^[10]

It’s important to understand that immunotherapy doesn’t work the same way for everyone. Some patients respond very well, with significant tumour shrinkage, while others see little benefit. Researchers are working to identify which patients are most likely to respond to these treatments so doctors can better predict who will benefit.

Genomic Research and Personalized Medicine

Advanced genetic testing of DSRCT tumours has revealed additional chromosomal changes beyond the characteristic EWS-WT1 fusion. One discovery is that some tumours have alterations in a gene called CCND1, which controls cell division. Understanding these additional genetic changes helps researchers identify new potential drug targets and develop more personalized treatment approaches.^[10]

Some clinical trials now include comprehensive genetic testing of each patient’s tumour to look for specific mutations or changes that might respond to particular drugs. This approach, called precision medicine, tailors treatment to the unique characteristics of each person’s cancer rather than treating all DSRCT patients the same way.

Where Clinical Trials Are Located

Clinical trials for DSRCT are conducted at specialized cancer centres around the world, including institutions in the United States, Europe, and other regions. Because this cancer is so rare, many trials accept patients from anywhere who are willing to travel for treatment. Major cancer centres such as Memorial Sloan Kettering Cancer Center, MD Anderson Cancer Center, and others with expertise in rare sarcomas often lead these research efforts.^[9]

Eligibility for clinical trials depends on many factors, including the patient’s age, overall health, previous treatments received, and specific characteristics of their tumours. Some trials are open only to patients who haven’t received prior treatment, while others specifically recruit patients whose cancer has returned after standard therapy. The research team carefully reviews each potential participant to ensure the trial is appropriate for their situation.

Most Common Treatment Methods

• Surgery
  • Cytoreductive surgery to remove as many visible tumours as possible from the abdomen and pelvis
  • May involve removal of portions of organs where tumours have grown, such as intestines or bladder
  • Often performed after chemotherapy has shrunk tumours to make removal easier
  • Frequently combined with HIPEC procedure during the same operation
• Chemotherapy
  • P6 regimen: multi-drug protocol developed specifically for DSRCT
  • Interval-compressed chemotherapy with shorter breaks between treatment cycles
  • Given before surgery to shrink tumours (neoadjuvant) or after surgery to kill remaining cells
  • Typical duration of several months with regular monitoring through scans and blood tests
• HIPEC (Hyperthermic Intraperitoneal Chemotherapy)
  • Heated chemotherapy solution circulated through the abdominal cavity during surgery
  • Lasts approximately two hours after tumour removal
  • Delivers high concentrations directly to cancer cells while minimizing body-wide exposure
  • Has shown improved survival rates when combined with surgery and systemic chemotherapy
• Radiation Therapy
  • Whole abdomen radiotherapy (WART) to treat the entire abdominal cavity
  • Whole abdominopelvic intensity-modulated radiation therapy (WAP-IMRT) for more precise targeting
  • Proton therapy available at select centres for even more focused treatment
  • Can be given before surgery to shrink tumours or after surgery to kill remaining cells
• Targeted Therapies (in clinical trials)
  • ONC-201: novel agent targeting specific cancer cell survival pathways
  • CDK4/6 inhibitors: drugs that block cell division proteins
  • Tyrosine kinase inhibitors including anlotinib
  • Drugs targeting EGFR, IGF-1 receptor, and other growth signals
• Immunotherapy (in clinical trials)
  • Antibodies targeting B7-H3 protein on tumour cells
  • Antibody-drug conjugates that deliver chemotherapy directly to cancer cells
  • Anti-GD2 and anti-HER2 antibodies
  • Androgen receptor blockers for tumours expressing these receptors

Treatment Duration and Long-Term Management

The complete treatment course for DSRCT typically extends over many months. A common sequence involves several months of chemotherapy, followed by surgery (often with HIPEC), then additional chemotherapy, and sometimes radiation therapy. The entire treatment process can take a year or more from diagnosis to completion of initial therapy.^[19]

After completing initial treatment, patients require close monitoring because DSRCT has a high rate of recurrence. Follow-up typically includes regular imaging scans—such as CT, MRI, or PET scans—every few months to check for signs that cancer has returned. The frequency of these scans may gradually decrease over time if no cancer is detected, but long-term surveillance continues for years.^[22]

If the cancer returns, treatment options depend on where it comes back, how much time has passed since initial treatment, and the patient’s overall condition. Some patients undergo additional rounds of chemotherapy, further surgery, or participate in clinical trials of experimental drugs. The medical team works with each patient to develop the most appropriate plan for managing recurrent disease.

Because DSRCT primarily affects young people, long-term quality of life is an important consideration. Treatments can cause lasting effects, including infertility from chemotherapy, digestive problems after extensive abdominal surgery, and potential organ damage from radiation. Many cancer centres offer comprehensive survivorship programs that address these long-term effects and provide rehabilitation services, including physical therapy, occupational therapy, nutritional counselling, and psychological support.^[22]

Supportive and Palliative Care

Throughout treatment and beyond, palliative care plays a vital role in maintaining quality of life for DSRCT patients. Palliative care focuses on relieving symptoms, managing pain, and providing emotional and psychological support. This type of care isn’t just for end-of-life situations—it can and should be provided alongside active cancer treatment from the time of diagnosis.^[3]

Palliative care teams include doctors, nurses, social workers, chaplains, and other professionals who work together to address physical symptoms like pain and nausea, emotional challenges such as anxiety and depression, and practical concerns including financial stress and family communication. They help patients and families navigate difficult decisions and maintain the best possible quality of life regardless of the cancer’s stage.

For younger patients, specialized child life specialists can help explain what’s happening using age-appropriate language, ease fears about medical procedures, and help maintain connections with school and friends during treatment. Social workers can assist with practical matters like transportation to appointments, lodging near treatment centres, and accessing financial assistance programs.^[22]

Support groups, either in-person or online, connect DSRCT patients and families with others facing similar challenges. Because this cancer is so rare, many patients feel isolated and benefit greatly from connecting with others who truly understand their experience. Several organizations maintain networks specifically for rare sarcoma patients and their families.

Prognosis and Survival

Desmoplastic small round cell tumour remains a very challenging cancer to treat. Current survival statistics show that between 15% and 38% of people diagnosed with DSRCT are alive five years after diagnosis. However, these numbers represent averages from past patients, and outcomes vary greatly depending on individual circumstances.^[3]

Factors that influence prognosis include how much tumour the surgeon can remove, whether the cancer has spread beyond the abdomen at diagnosis, how well the tumours respond to chemotherapy, and the patient’s age and overall health. Patients whose tumours can be completely or nearly completely removed during surgery, combined with aggressive chemotherapy and possibly HIPEC, tend to have better outcomes than those with widespread disease that can’t be fully removed.^[19]

Some patients do achieve long-term survival, living many years after diagnosis with no evidence of disease. Research continues to identify what factors contribute to these better outcomes so that more patients can benefit from the most effective treatment approaches. Every patient who participates in clinical trials and allows their medical information to be studied contributes to improving future treatments.

It’s important to remember that statistics describe populations, not individual people. Some patients with challenging circumstances do much better than expected, while others with seemingly favourable situations face setbacks. The medical team can provide information about what to expect, but no one can predict with certainty what will happen for any individual patient.