08. PTC: Cancer Risks for Kidney Recipients
Why am I at greater risk of developing cancer after kidney transplant?
All organ transplant recipients are at heightened risk of developing cancer after transplant. This is because although life-sustaining, long-term use of immunosuppressant drugs lowers the body’s ability to fend off certain cancers. When you are taking immunosuppressant drugs, your immune response is lowered, and this is what helps to prevent your body from rejecting your new kidney. It also means that your body is less able to recognize and destroy cancer cells or infections that can cause cancer.
Additionally, because immunosuppressant drugs reduce your body’s natural monitoring and disease response, you are at increased risk of developing certain viral infections that are linked to increased cancer risk. Examples of these viruses include the Epstein-Barr virus which is associated with lymphoma, Hepatitis which is linked to liver cancer, the Herpes virus which is associated with Kaposi sarcoma, and the Human Papilloma Virus that is associated with skin cancers. There is also a very small chance that cancer was already present in the transplanted organ.
For all people, cancer risk increases as a natural part of the aging process. For kidney transplant recipients, the risk increases with each year of immunosuppressant drug use. This means that the longer kidney transplant recipients survive post-transplant, the greater the frequency of cancer. There are also certain lifestyle choices that can raise your risk of cancer, such as not getting regular exercise, smoking, or having a poor diet.
A popular notion among recipients is that "cancer comes packaged with the transplanted organ." While this is possible, it is not the most common reason for someone to develop cancer after receiving a kidney transplant. Here are some more likely explanations:
- Immunosuppressive therapy: As you might know, getting a kidney transplant entails being on medications to suppress your immune system. Usually, these medications need to be continued indefinitely. Certain kinds of medications used for this purpose after the transplantation might increase your risk more than others. For instance, immunosuppressant medications which target certain kinds of white blood cells (e.g. OKT3 or antilymphocyte serum) will significantly increase the risk of something called "post-transplant lymphoproliferative disorder" or PTLD. However, more frequently, it is the overall extent/level of immunosuppression induced by being on multiple different immune suppression medications, rather than the quality of one specific drug, which increases cancer risk.
- An easier way to understand this concept is to realize that cancer cells are constantly being produced in our bodies, in general. The reason we don't develop a new malignancy every day is that these "lone-wolf" cancer cells are identified by our immune system surveillance and destroyed at the very outset. Therefore, our immune system is not just a protective mechanism against infections, it is also a protective mechanism against aberrant cell production (which could later turn into cancer). Suppressing this very immune system will therefore increase cancer risk.
- Infections: Certain viral infections specifically increase risk of cancers. Kidney transplant recipients face a greater risk of viral infection because of an immunosuppressed status. Viruses multiply by taking over and tinkering with our cells' replication machinery (the DNA in some cases). This may be one possible explanation for why viral infection increases cancer risk. Examples of these viruses include the Epstein-Barr virus (which increases risk of lymphoma), the Human Herpes Virus-8 (associated with Kaposi sarcoma), and Human Papilloma Virus (associated with skin cancers).
Which cancers am I at greater risk for, and how high is my risk?
Here are a few the common cancers you may be at risk for as a kidney recipient. The relative risk of each of these cancers depends on the number of immunosuppressive medications you need to take, the dosage of these medications, and other things like your diet and exercise. Below you can read about some of the specific types of cancers you may be at risk for like skin cancer, lymphomas, breast and cervical cancer, thyroid cancer, lung cancer, liver cancer and kidney cancer among others. Explore the look pages to learn more about each of these types of cancer and how to manage your risk.
- Skin Cancer: Kidney transplant patients are three times more likely than other people to get skin cancers after a transplant. This makes it very important for people who have had a transplant to use a strong ‘sun block’ cream to avoid sunburn. If skin cancers are diagnosed in good time, they are not usually a major problem. This type of cancer does not usually spread to other parts of the body, and can be easily removed. There is a possibility that an anti-rejection drug called sirolimus has an additional effect against cancer, and that a switch to sirolimus should be made if someone with a transplant gets a skin cancer. Most doctors will at least reduce the doses of anti-rejection drugs overall if someone has a skin cancer.
- Lymphoma: A small number (2-5%) of kidney transplant patients develop a more serious cancer called lymphoma, sometimes also called ‘post-transplant lymphoproliferative disease’ (PTLD). This cancer is the growth of white blood cells in the body’s immune system (mainly in the spleen and lymph nodes). There are several lines of treatment, and the needs of each affected individual will need to be carefully assessed by kidney specialists and lymphoma specialists. Some lymphomas will go away if the anti-rejection drugs are stopped, there is a risk that rejection of the transplant will occur but this is not always the case. Some lymphomas will respond to drugs (chemotherapy) or X-ray treatment (radiotherapy), and anti-rejection drugs can be continued, possibly with a lower dose.
- Cervical Cancer: Women are at increased risk of cervical cancer after a kidney transplant. Checks for cervical cancer with cervical smears (PAP smear) should be performed just as often as suggested for the general population. Cervical cancer can be detected in the very early stages by cervical smears and should be almost entirely preventable.
- Breast Cancer: Breast cancer occurs at about the same rate in kidney transplant patients as in the general population. However, because breast cancer is quite common, transplant patients should pay special attention to their breasts, with self-examination and at breast screening clinics. In addition, research has shown that transplant patients commonly develop non-cancerous breast lumps, but even if these turn out to be false alarms, it is vital to get any abnormalities checked out by your doctors.
Note: From the full research study article found in RELATED LINKS below:
"Cancer incidence rates were almost three times higher as compared to the matched general population. Significantly increased SIRs were observed for renal cell carcinoma, post-transplant lymphoproliferative disorder, prostate cancer, bladder cancer, thyroid cancer and melanoma. Independent pre-transplant risk factors for cancer-free survival were age <52.3 years, age >62.6 years, polycystic kidney disease other than autosomal dominant polycystic kidney disease (ADPKD), high body mass index in kg/m2, ADPKD and diabetic nephropathy. G-chart analysis identified relevant changes in the detection rates of cancer during aftercare with no significant relation to identified risk factors for cancer-free survival."