The kidneys are a pair of organs that act as your body’s detox system. “They’re responsible for removing excess water and toxins [a.k.a. waste products] through your urine,” says Sandy Srinivas, M.D., professor of medicine, oncology and urology, at Stanford University in Stanford, CA. “They also maintain a healthy fluid balance of water and electrolytes like salts, calcium, and potassium. Large amounts of blood also get infiltrated through the kidney where it gets purified.”
But things can go wrong with this mighty machine. Kidney cancer is one of the 10 most common cancers and about 80,000 people are diagnosed per year, according to the American Cancer Society. What’s particularly worrisome about a kidney cancer diagnosis is that a kidney tumor can be hard to discover until it’s already advanced—meaning the cancer has spread to the renal vein where it can escape through the bloodstream or lymphatic system and spread to other parts of the body, most commonly the lungs, bones, and the brain. “In this regard, kidney cancer is like a pregnant uterus. It can grow and only in the later stages does it become apparent, It’s very rare that the tumor is something you can feel,” says Dr. Srinivas.
While detection can be elusive, common risk factors for kidney canceridney-cancer/causes-risks-prevention/risk-factors.html are not—and include, smoking, obesity, and high blood pressure even if you are on medication to lower it. “An inherited gene mutation is a less common factor at between 5% to 10% [of cancer cases],” says Nirmish Singla, M.D., a urologic oncologist at The Johns Hopkins Hospital, in Baltimore, MD.
Fortunately, within just the last five years, targeted and immunotherapy treatments “have revolutionized kidney cancer outcomes, compared with the past,” says Dr. Srinivas, especially when it comes to metastatic disease.
Let’s take a closer look at how kidney cancer spreads in the body—and what you can do about it.
From Kidneys to Blood Vessels
If cancer cells spread beyond the kidney to other areas of the body, this becomes advanced or stage 4 kidney cancer. Sometimes, advanced cancer begins when a tumor grows on the adrenal glands, which sit right on top of the kidney that has the cancer. “In this case, we would just remove it because you have another adrenal which can do the job of both,” says Dr. Srinivas. “Even two can be removed and most patients do fine on adrenal hormone replacement.”
Another way cancer advances is through the blood, says Dr. Srinivas, adding that 30% of kidney cancers get to the metastatic stage.
Kidney cancer can also spread through the lymphatic system, an infection-fighting group of organs that include lymph nodes, says Dr. Singla. Unlike the often undetectable kidney tumors, you may feel a tumor that’s on your lymph node pressing painfully on surrounding tissues, particularly in your neck or under your arm.
Systemic immunotherapy or targeted therapy or a combination is the standard for all sites. Immunotherapy works by helping your immune system better fight cancer cells throughout your body, instead of just in one spot. “Then, in some cases, we may surgically remove the tumor. Local radiation as an option in some circumstances,” says Dr. Srinivas.
How Advanced Kidney Cancer Affects Your Lungs
About 25% to 30% of patients have distant metastases when they are first diagnosed with kidney cancer, meaning the cancer has spread to organs in other parts of the body. The lung is the most common site of the spread, according to the National Library of Medicine.
Kidney cancer can spread to the lungs in two ways: “Since kidney tumors grow largely undetected, healthy people who have never been diagnosed with cancer might start experiencing shortness of breath, a dry cough that’s persistent and isn’t going away, and possibly eventual coughing and spitting up blood,” says Dr. Srinivas. “A CT scan may reveal multiple spots in the lung and a big tumor in the kidney.”
Or you might have had kidney cancer previously and had a kidney removed. “And following the surgery you’re cleared that the cancer has not spread further and you continue to be followed by your doctors. It is possible that years later another tumor develops elsewhere, like on your lung, lymph node or adrenal gland,” says Dr. Srinivas.
“Regardless, when a pathologist looks at a biopsy, they can tell us if the cancer started in the lung or someplace else and went to the lung,” says Dr. Srinivas. Lung metastases and other cancers that spread from the kidneys are all treated with immunotherapy or targeted therapy. Surgery is also an option in some cases, says Dr. Singla.
When Kidney Cancer Spreads to Your Bones
When kidney cancer spreads to the bones, one sign might be a fracture that results just from doing an everyday task like, for instance, lifting a bag of groceries that results in a broken humerus in the arm. “You’re feeling like there’s no reason for the break to have happened but the area’s actually been weakened by the cancer,” explains Dr. Singla. A lot of bone pain throughout the body is another symptom. It can spread to just one bone site (a solitary metastasis) or to multiple bones.
Systemic immunotherapy is the first line of treatment and sometimes surgery. “Additional radiation may be used to improve pain and help you move better and to reduce the risk of fractures, “says Dr. Srinivas.
How Advanced Kidney Cancer Affects the Brain
“Most people with kidney cancer don’t have metastasis to the brain. But 15% of patients with advanced kidney cancer do,” says Dr. Singla. It is not entirely clear why certain cancer types have the ability to spread to certain sites. Dr. Singla is currently leading a study in an effort to learn why, “compared to other cancers, renal cell carcinoma has a unique ability to spread to nearly any site in the body, and more specifically, the brain.”
In his study, “Tumor Evolution of Brain-Specific Tropism in Metastatic Renal Cell Carcinoma,” Dr. Singla is exploring a ‘seed-and-soil’ hypothesis, rather than a random migration. “There might be aspects of the tumor itself (the seed) that drive it to the brain (the soil) which may also have characteristics that enable successful colonization (metastasis),” explains Dr. Singla.
Clues that the cancer has spread to the brain are varied and numerous such as headache, weakness in an arm or leg, facial drooping, trouble with walking coordination, and stroke.
“Depending on many factors, treatment involves some combination of surgery, stereotactic radiotherapy (radiation beams targeted directly at the brain metastases) and immunotherapy,” says Dr. Singla. Still, brain metastases are difficult to treat. Surgery is limited to selected patients, and many people may still develop new sites of disease even after surgery, Dr. Singla says. Patients with these metastases are also frequently excluded from clinical trials, “making outcomes difficult to study,” he adds.
Hope for People With Advanced RCC
Today, about 75% of people with kidney cancer will be alive five years after diagnosis, according to the National Cancer Institute. The statistics for metastatic disease are less optimistic—about a 15% five-year survival rate, according to the American Cancer Society. But that number is significantly better than a decade ago and keeps improving all the time.
That’s largely due to evolving kidney cancer research. For example, although there isn’t a test to diagnose kidney cancer early before symptoms develop, researchers are working on developing blood or urine tests—sometimes called liquid biopsy tests—to detect small early-stage kidney cancers.
“When patients get a diagnosis of an advanced [kidney] cancer it’s important for them to recognize that they can still very much live a normal life,” says Dr. Srinivas. “Many people are on these treatments for a long time. So much so that kidney cancer is viewed more like a chronic illness today.”
https://www.healthcentral.com/condition/kidney-cancer/how-advanced-kidney-cancer-spreads
