Andrew Siegel, MD Blog #110
This blog is dedicated to my friend Shira Litvin, host and producer of “Best In Health Radio” (www.BestInHealthRadio.com), who recognized the critical importance of this disease and prodded/begged/nagged/coerced me to address this subject.
(Continued from last week)
Conventional urological teaching is that a solid mass in the kidney is a cancer until proven otherwise. However, not all solid kidney masses are cancers. It is possible to have a kidney tumor that is benign, e.g., an “oncocytoma” or an “angiomyolipoma.” Kidney cancer needs to be distinguished from the much more common kidney cyst. A kidney cyst is a sac containing fluid that is within the kidney or attached to the kidney. They are very common, occurring in about 50% of adults over 50 years of age and can be quite variable in size. Most have the appearance of water balloons, are benign, and rarely evolve into a problem. A simple cyst has a thin wall and no subdivisions (referred to as “septa”), calcifications, or solid components. If a cyst has septa, calcifications, or wall thickening, it is known as a “complex” cyst and generally needs to followed carefully and regularly and perhaps operated upon. On occasion, a kidney cancer can be a malignant cystic mass, although most kidney cancers are solid (containing tissue) as opposed to kidney cysts (containing fluid).
Most kidney cancers occur on the basis of sporadic mutations in kidney cells during the process of cellular replication. Cancer begins when kidney cells acquire mutations in their DNA. The mutations direct the cells to grow and divide rapidly and in unchecked fashion, with the accumulating abnormal cells forming a mass. Ultimately, these cells can extend beyond the kidney and some cells can break off and spread (metastasize) to remote parts of the body, including the bones, chest, liver and brain. Tobacco and obesity have been established as environmental risk factors for kidney cancer.
There are genetic/familial forms of kidney cancer including von-Hippel-Lindau disease and familial papillary renal cell carcinoma. In general, hereditary forms of kidney cancer occur at an earlier age than those that occur on the basis of mutations. Furthermore, with the hereditary forms of kidney cancer, it is not uncommon to have multiple kidney tumors present, sometimes present in both kidneys. Certain populations are particularly high risk for kidney cancer. People with end-stage-kidney disease (renal failure) who are on dialysis are in this group as are those with familial/hereditary kidney cancer. Those with tuberous sclerosis have a propensity for developing kidney cancers.
Many kidney tumors have a very rich blood supply. Interestingly, some kidney cancers can give rise to a strange set of symptoms known as “paraneoplastic syndromes,” in which symptoms remote from the kidney occur, making the diagnosis confusing. These syndromes can be high blood pressure; anemia; high red blood cell count; high calcium levels in the blood; elevated liver function tests; fever; etc.
Kidney cancers are commonly referred to as renal cell carcinomas-RCC. They can be “staged” to demonstrate the extent of the disease by using imaging studies including CT or MRI. Stage I means confined within the capsule of the kidney; Stage II invades the fatty envelope surrounding the kidney; Stage III involves the lymph nodes in the region; Stage IV is distant spread of tumor. Prognostic factors include stage, size, nuclear grade (a description based on how abnormal the tumor cells and the tumor tissue look under a microscope), and histological sub-type of cancer. In general, the lower the stage, the smaller the size, the lower the grade all portend a better prognosis.
In terms of sub-types of kidney cancer, clear cell RCC is the most common form, accounting for about 70% of those with renal cell carcinoma. When seen under a microscope, the cells that make up clear cell renal cell carcinoma look very pale or clear. Papillary RCC is the second most common subtype. These cancers form little finger-like projections (papillae). Pathologists refer to this as chromophilic because the cells take up certain dyes and appear pink under the microscope. Chromophobe RCC accounts for about 5% of kidney cancers. The cells of these cancers are also pale, but are much larger, and this particular kind of kidney cancer has the best prognosis.
The treatment of early, localized kidney cancer is surgical. Years ago, this meant complete removal of the kidney. This is still the case with a large cancer or a central one that affects the key blood supply, but in many cases it is possible to do a “partial” nephrectomy and spare kidney tissue. Nowadays, this is often done using laparoscopy with robot assistance. Not all kidney masses need to be removed as some can be observed and if they do not change in size or character over time, it is unlikely malignant. Thermal ablative therapies are also possible for smaller kidney masses—using either heat (radiofrequency waves) or cold (cryosurgery) placed directly into the mass via CT guidance. It is often possible to biopsy the mass prior to the ablative therapy using a fine needle via CT guidance. Kidney tumors in general respond poorly to radiation therapy and chemotherapy, but there are numerous effective alternative therapies for advanced disease including immunotherapy including and targeted therapies.
Targeted therapies are drugs that interfere with the growth of cancer cells at a molecular level. These drugs interfere with cell growth, prevent cell replication, or disrupt the blood supply to the cancer cells. Sorafenib and Sunitinib disrupt the blood supply, depriving the tumor of oxygen and nutrients; Temsirolimus and Everolimus block blood supply as well as interfere with cell growth; Pazopanib and Axitinib are additional targeted medications.
Bottom Line: What to do to try to minimize risk and make an early diagnosis of kidney cancer?
· Stay fit and healthy by eating well and exercising regularly
· Avoid tobacco
· Avoid obesity
· Avoid kidney failure (renal failure) as kidney cancer is much more prevalent in patients on dialysis. The two leading causes of kidney failure are diabetes and high blood pressure, often but not exclusively on the basis of poor lifestyle choices. Diabetes and high blood pressure frequently respond well to a lifestyle “angioplasty” including weight loss, exercise and healthy eating habits. If they do not respond to lifestyle optimization, they can most often be managed well with medications.
· Don’t ignore symptoms that persist and are not normal for you: blood in the urine; flank pain; etc.
· Although controversial, a non-invasive screening sonogram (ultrasound) of the abdomen can easily pick up an early kidney tumor as well as a host of other problems (liver, gallbladder, spleen, pancreas, aorta, bladder, prostate, ovaries, uterus). Although it may not be cost-effective for a population at large, if it is you or a loved one who has a potential serious problem picked up, then it is certainly more than cost-effective!
Andrew Siegel, M.D.
Author of Promiscuous Eating: Understanding and Ending Our Self-Destructive Relationship with Food: www.promiscuouseating.com
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