What Type of Kidney Cancer Do You Have?
Kidney cancer is on the rise in the U.S. According to the American Cancer Society (ACS), 73,750 Americans were diagnosed with this disease in 2020. There are different kinds, but the most common is renal cell carcinoma (RCC), which accounts for 90% of cases. The other 10% comprise a mix of rare cancers. Experts credit the increase (at least in part) to the growing use of imagining scans like MRIs, which may catch tumors in earlier stages. The obesity epidemic may play a role, too. We'll break out the types of kidney cancer and explain their treatments.
Kidney Cancer Basics
The kidneys are located behind your abdominal organs on either side of your spine. They play the crucial role of filtering and then flushing out waste in the urine. When kidney cancer strikes, larger tumors can sometimes lead to blood in the urine or cause lower back pain on one side. Still, many people experience no symptoms at all. Tumors are often found during routine exams, or when doctors are looking for something else, says Brian Shuch, M.D., director of the Kidney Cancer Program, University of California, Los Angeles.
Renal Cell Carcinoma
Again, 9 out of 10 kidney cancers are diagnosed as renal cell carcinoma (RCC), where cancerous cells grow in the lining of the kidney’s tubules (small tubes that help filter blood, excrete waste, and make urine). There are actually three different kinds of RCC, according to the ACS. Most common is clear cell RCC (named for tumor cells that looked like clear bubbles), which comprises roughly 75% of all RCC cases. Papillary RCC (named for cancer cells with fingerlike projections) makes up 13% to 20%, with chromophobe RCC diagnosed in 5% of RCCs. A few super-rare, unclassified RCCs are occasionally diagnosed, too.
Treatment for Early-stage RCC
When RCC is caught early enough (before it metastasizes, or spreads beyond the kidney), surgical removal of the cancerous kidney (a procedure known as nephrectomy) is often the main treatment—and it can be the cure. Another treatment is ablation, which destroys cancer cells by freezing or burning them. Ablation has low side effects and can be given as an outpatient procedure. Still, the cure rate from a single ablation may not be as high as surgical removal. Plus, not all tumors are suitable for ablation, according to Johns Hopkins.
Treatment for Later-stage RCC
For stage 4 (metastatic) RCC, surgery and radiation together can be effective. Plus, advanced clear cell RCC often responds well to systemic treatments, including chemotherapy and immunotherapy (the latter deploys the body’s own immune system to fight cancer cells), as well as targeted therapy, which uses drugs to go after specific genes involved in cancer-cell growth. However, RCCs may develop resistance to treatment and may return locally—but some recurring cancers can be treated effectively with surgery plus systemic therapies, according to CancerConnect.
Urothelial carcinoma is among the 10% of kidney cancers that are not RCC. “Urothelial carcinomas are very different from renal cell carcinomas,” says Pavlos Msaouel, M.D., assistant professor of Genitourinary Medical Oncology at MD Anderson Cancer Center in Houston. “They’re managed differently and have different prognostic considerations.” This cancer targets cells inside the urethra and the ureter (the tube connecting the bladder with the kidney). Most UCs grow in the bladder, but it’s considered kidney cancer when it's found in the renal pelvis or high up in the ureter, he explains.
Urothelial Cancers Can Make It Difficult to Pee
RCC and UC can also sometimes share similar symptoms, like blood in the urine. However, “if the urothelial carcinoma arises from the urethra or bladder, then it can produce symptoms such as urinary obstruction, which is rarely seen with RCC,” says Dr. Msaouel. If you have a weak or interrupted stream, or abdominal pain, your doctor will give you an ultrasound or a CT scan to see if a UC obstruction is to blame.
Treatment for Urothelial Carcinoma
Treatment for UC is determined by its stage. For stage 0, a transurethral resection (TUR), where a doctor inserts a cystoscope to remove the mass, may be all that is needed. For a stage 1 tumor, a TUR, followed by chemotherapy, is standard. While chemo doesn’t work well against most RCCs, “it’s a time-honored therapy for urothelial carcinoma,” says Dr. Msaouel. Stages 2 and 3 often require a partial or total removal of the bladder, followed by chemo. For stage 4, chemo and immunotherapy are the main treatments; targeted therapy is also sometimes considered.
Sarcoma of the Kidney
Kidney sarcoma makes up fewer than 1% of all kidney cancer cases, explains Dr. Msaouel. A carcinoma grows in the cells that line the body’s internal organs (or in the skin). A sarcoma grows in the body’s connective tissue, including fat, muscles, and deep skin tissues. Kidney sarcoma develops in the connective tissue or fat surrounding the kidney. Due to the very aggressive nature of the tumor, kidney sarcoma is often diagnosed quite late, requiring surgery and chemotherapy.
Treatment for Kidney Sarcoma
Scientists aren’t sure exactly what causes kidney sarcoma, but research has found that DNA mutations in soft-tissue sarcomas are common. Mutations are thought to be acquired during life from, say, exposure to cancer-causing chemicals or radiation, rather than inherited before birth, according to the ACS. This cancer is usually treated with surgery—or a combo of surgery and chemo if it recurs. Because kidney sarcoma tends to grow quickly and produce large tumors that are difficult to remove entirely, metastasis and recurrence are likely.
Wilms tumor is a kidney cancer that develops primarily in children between the ages of 2 and 5, says Dr. Shuch. Nearly all cases are diagnosed before the age of 10. According to Medline data, incidence varies among populations, “with African Americans having a higher-than-average risk of developing it,” for reasons unknown. Wilms tumor is often first noticed during a physical exam as abdominal swelling or a mass in a kidney. Other possible symptoms include fever, nausea, loss of appetite, and blood in the urine
Treatment for Wilms Tumor
Treatment for Wilms tumor is decided based on the stage and how biopsied cells look beneath a microscope. Tumor size, the child’s age, and any DNA changes are also considered. Surgery is generally the first-line approach, with the goal of removing the primary tumor, even if the cancer has spread. At stage 3, the tumor can no longer be removed entirely, so chemo is used before surgery to shrink the cancer. Even children with advanced tumors experience a four-year survival rate of 85% to 100%.
Primary Renal Lymphoma
According to the National Institutes of Health, primary renal lymphoma (PRL) is defined as a non-Hodgkin's lymphoma involving the kidney. “In very rare cases, lymphoma may arise from the kidneys,” says Dr. Msaouel. (It’s so rare, its very existence has been debated in the past, although as of 2016 up to 70 cases were reported.) PRL usually presents as a lone tumor mass in the kidney and may include enlarged regional lymph nodes. When it strikes, “the disease should be managed more like a lymphoma and not like a renal cell carcinoma or a sarcoma,” he explains.
Benign Kidney Tumors
Some good news: Benign tumors don’t have the ability to metastasize. Still, these tumors are often removed, anyway. UCLA Health describes three different kinds of benign kidney tumors, including renal adenoma (a small, slow-growing mass of less than 1 cm); oncocytoma (a non-spreading renal tumor that can resemble kidney cancer on a biopsy); and angiomyolipoma (a tumor containing fat, vessels, and muscle). Larger benign tumors can bleed, so treatment is advised when they are more than 4 cm (the size of a large walnut)—surgical removal of the affected kidney is usually performed.
No Matter the Type, Help is Available for Kidney Cancer
Obviously, if you find blood in your urine, call your doctor right away and ask to be screened for kidney cancer (although this symptom can certainly mean other things, too). If you are diagnosed with kidney cancer—any of the types described here—it may come as a total surprise, since many people never experience anything other than lower back pain as a warning sign. But know this: Dr. Msaouel reassures that when caught early, most renal cell carcinomas (remember—that’s 90% of all cases) are treated successfully—and have very good prognoses.
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