Renal medullary carcinoma (RMC) is a rare type of kidney cancer. In the U.S., it is usually found in younger Black people.
RMC forms in a part of the kidney called the renal medulla. About 70% of cases develop in the right kidney.
All RMC cells have lost the ability to make a protein called INI1 (also known as IN-1, SMARCB1, hSNF5 and BAF47). This protein normally stops tumors from forming.
To diagnose RMC, tumor tissue should be examined for the presence of INI1. If the tissue has this protein, then the cancer is not RMC. If the cancer cells are negative for INI1, it may be RMC or another cancer that also does not produce INI1. Additional tests will be needed to get a definitive diagnosis.
Because RMC is rare and hard to identify, it is important that the tumor tissue be evaluated by a pathologist (a doctor who specializes in diagnosing disease) with experience diagnosing the disease.
RMC and sickle hemoglobinopathies
In most cases, RMC is also linked to genetic mutations that can cause red blood cells to become rigid with a curved shape that looks like a sickle. These disorders are called sickle hemoglobinopathies.
The most common sickle hemoglobinopathy is the sickle cell trait. People with sickle cell trait usually have no other symptoms and live normal lives. Many individuals with sickle cell trait do not know they have it. Patients diagnosed with RMC should undergo a special blood test to determine if they have sickle cell trait or other sickle hemoglobinopathies.
In the U.S., the sickle cell trait is most common among Black people, so RMC is usually found in this group. Most cases are diagnosed in people in their teens and twenties.
In rare cases, RMC occurs in individuals who do not have any sickle hemoglobinopathies. This is a rare RMC subtype that may be called renal cell carcinoma, unclassified with medullary phenotype (RCCU-MP). Treatment of RCCU-MP is often like the treatment for RMC that is associated with sickle hemoglobinopathies.
Less than 1% of kidney cancers are diagnosed as RMC. Because the disease is rare and hard to recognize, the number of cases is likely higher.
RMC patients are often misdiagnosed with another condition, including other types of kidney cancer. It is critical to correctly diagnose RMC because the disease does not respond to the medications that treat most other kidney cancers.
Because RMC is aggressive and often diagnosed late, after the disease has spread, few patients today survive more than two years.
Awareness of RMC has increased in recent years, so the number of patients diagnosed with the disease has grown. Treatment of RMC has also improved recently. More patients are being diagnosed earlier and doctors have developed new ways to fight the disease. At one point, less than half of patients with RMC survived more than a year from diagnosis. Today, with proper management using current therapies, most patients survive beyond one year. Some patients have even been completely cured by these new treatments. Research and clinical trials are underway to continue improving care for patients with RMC.
Renal medullary carcinoma risk factors
A risk factor is anything that increases the chance of developing a particular disease. The risk factors for RMC include:
- Sickle hemoglobinopathies: People with sickle hemoglobinopathies have increased risk for RMC. The most common sickle hemoglobinopathy is the sickle cell trait. Other sickle hemoglobinopathies that increase the risk for RMC include sickle cell disease (also known as sickle cell anemia), hemoglobin SC disease, or sickle beta thalassemia.
- Race/ethnicity: In the U.S., Black people are more likely to develop RMC because the sickle cell trait is most common in this group. The sickle cell trait is also common in people from certain regions of Greece, southern Turkey, central India, eastern Brazil, the Dominican Republic, eastern Saudi Arabia and equatorial Africa.
- Very intense exercise: Doctors believe that very intense exercise can trigger RMC, especially in people with the sickle cell trait. However, moderate exercise may actually prevent RMC while producing many other health benefits.
- Age: Most cases of RMC are in people under age 30.
- Gender: Men are twice as likely to develop RMC than women.
Renal medullary carcinoma symptoms
Symptoms of RMC may include:
- Blood in the urine, also known as hematuria. This is the most common symptom of RMC.
- Pain on the side and back between ribs and hips.
- Unintentional weight loss.
- Night sweats.
These symptoms do not mean you have RMC. However, it is important to discuss any symptoms with your doctor, since they may signal other health problems.
Renal medullary carcinoma diagnosis
RMC is a rare disease, and it is often misdiagnosed as other kidney cancers. The treatments for these other cancers do not work on RMC, so an accurate diagnosis is essential.
MD Anderson has pathologists dedicated to diagnosing kidney diseases. Since MD Anderson is home to the largest RMC program in the world, our pathologists are among the most experienced in recognizing this rare disease.
The following tests may be used to diagnose RMC and monitor the patient during treatment.
During a biopsy, a small tissue sample is removed and examined under a microscope for cancer cells. This is the only way to definitively diagnose RMC. Doctors perform most RMC biopsies using a live ultrasound or CT image to guide a needle to the tumor. The needle then takes a small sample of the suspected cancer tissue for examination.
Imaging exams are used to look for cancer inside the body. They can help locate tumors, see if the cancer has spread from its original site and track how the body is responding to treatment. There are many types of imaging exams.
The most common imaging exam for RMC is the CT scan.
CT scans use an X-ray machine to take several pictures from different angles, providing a highly detailed image. For patients with RMC, doctors take a CT scan of the kidney. They should also scan the abdomen and the pelvis to see if the cancer has spread to other parts of the body.
Blood and urine tests
These tests are used to monitor patients’ health and track how they are responding to treatment.
Renal medullary carcinoma treatment
The following treatments are used for people with RMC.
Chemotherapy drugs kill cancer cells, control their growth or relieve disease-related symptoms. Chemotherapy may involve a single drug or a combination of two or more drugs, depending on the type of cancer and how fast it is growing.
Chemotherapy is the first treatment for most patients with RMC. If the tumor shrinks enough from chemotherapy, the patient may then undergo surgery.
The entire kidney is usually removed in RMC surgery. This is called a radical nephrectomy. The organ is removed because RMC tumors are located deep in the kidney. In addition, these tumors do not have clear borders, so cancer cells mix with healthy cells. If the surgeon tried to remove the tumor only, cancer cells could be left behind.
Radiation therapy uses powerful, focused beams of energy to kill cancer cells. There are several different radiation therapy techniques. Doctors can use these to accurately target a tumor while minimizing damage to healthy tissue.
Radiation treatments for RMC include:
- Intensity modulated radiation therapy (IMRT), which focuses multiple radiation beams of different intensities directly on the tumor for the highest possible dose.
- Stereotactic body radiation therapy (SBRT), also known as stereotactic ablative radiotherapy or stereotactic ablative body radiation (SABR). SBRT precisely targets tumors with very high doses of radiation. It achieves this by using several radiation beams of various intensities aimed at the tumor from different angles. Learn more about SBRT.
- Proton therapy. Proton therapy is similar to standard radiation therapy, but it uses a different type of energy that may allow doctors to target tumors with much more accuracy. This limits damage to nearby healthy tissue and allows for the delivery of a more powerful dose of radiation. Learn more about proton therapy.
Clinical trials are a key component of MD Anderson's mission to end cancer. MD Anderson uses clinical trials to find better ways to prevent, diagnose and treat cancer. Doctors use treatment trials to learn more about how to fight cancer.
MD Anderson designed and conducted the first clinical trials dedicated exclusively to RMC. Your doctor may offer you a clinical trial as a treatment option.
Why choose MD Anderson for your renal medullary carcinoma treatment?
Renal medullary carcinoma is a rare cancer. Most oncologists see only a few RMC patients in their entire careers. MD Anderson treats dozens of patients with RMC every month.
This gives our doctors incredible expertise in this disease, starting at diagnosis. MD Anderson has pathologists dedicated exclusively to diagnosing kidney cancer. This allows them to identify a disease that is often misdiagnosed.
After diagnosis, you will work with a team of kidney experts. This team will include a surgeon, radiation oncologist and medical oncologist. They work closely together to plan and coordinate your treatment.
MD Anderson is also a leader in RMC research. The first clinical trial dedicated to finding new treatments for the disease was conducted here. Our physicians and scientists continue to research new ways to treat RMC. The newest and most promising therapies for RMC are often tested first at MD Anderson. MD Anderson also follows the largest number of patients with RMC who have been cured of their disease.
And at MD Anderson you will also be surrounded by the strength of one of the nation's largest and most experienced cancer centers. From support groups to counseling to integrative medicine care, we have all the services needed to treat not just the disease, but the whole person.