Testicular Cancer and CT Scans

How much radiation is safe?

Examples of CT images.

What are CT Scanners and How Do They Work?

CT scanners use x-ray radiation to create high resolution image of the human body. An x-ray tube emits the radiation which passes through the human body and is then picked up by detectors on the other side. The x-ray tube typically moves in a helical pattern about the body and computer software is able generate detailed images of the anatomical structures of the individual being scanned.

Testicular Cancer and CT Scans

CT scans are frequently utilized in the management of testicular cancer.  They are typically used following surgery to determine if the cancer has spread to any regions outside the testicle, such as lymph nodes or lungs. They are used after treatment to see if the cancer has returned/spread. Following recommendations of the National Comprehensive Cancer Network (NCCN), a patient with testicular cancer can expect to have at least 2 to 10 CT scans in the first 5 years following diagnosis, depending on the cancer type and stage.

Measuring Radiation

One common measurement of radiation is the millisievert (mSv). In the United States, the average person is exposed to about 3.6 mSv every year simply from background radiation. The most common CT scan for a testicular cancer patient is a scan of the pelvis and abdomen, with or without the chest. This typically exposes the individual to about 10 mSv for the study.

Most testicular cancer patients can expect to receive about 20-100 mSv of radiation for the first 5 years following diagnosis. This can be considerably higher if the cancer returns and more scans are required.

What is the Concern Regarding Radiation?

X-ray radiation is a type of ionizing radiation. Ionization is the process of an atom gaining or losing electrons to then assume positive or negative charges.

These charged atoms can result in cellular and DNA damage. This damage can result in mutations, which may ultimately result in the development of cancer. There is no such thing as a "safe" dose of radiation as even small amounts could theoretically result in damage and subsequent cancer. Studies involving survivors of the atomic bomb in Japan suggest that doses greater than 50-100 mSv significantly increase the risk for cancer. There does seem to be a correlation between increasing doses of radiation and higher incidences of cancer.

The biggest concern is if CT scans for testicular cancer patients could ultimately result in secondary cancers further down the line. Research has shown that testicular cancer survivors are at increased risk for secondary cancers. This risk appears to be about 1.4-2.8 times greater than the risk of the general population1. However, there has been no direct cause and effect relationship established between CT scans and secondary cancers. Many patients also receive chemotherapy, which is also a risk factor for secondary cancers, making it difficult to ascertain what actually caused a new cancer further down the road.

The Benefit of CT Scans for Testicular Cancer

A CT scan should only be done if there is a very good reason to do it.

With testicular cancer, there are several good reasons that justify the use of CT scanning despite the potential risks of the radiation received. First of all, it is essential to perform a CT scan after surgery to know if the cancer has already spread to lymph nodes, lungs or elsewhere. Testicular cancer can be cured even when it has spread, but it is not known whether it has spread without the use of a CT scan. Even when the initial CT scan does not show that the cancer has spread anywhere else, it may spread at a later date, making further assessments with CT scans necessary. The sooner the cancer is detected, the better the prognosis.

Testicular cancer has a significantly worse prognosis if more tissues are involved.

As with anything in medicine, it is a balance between the benefit and the risk. Please discuss any concerns or questions regarding CT scan radiation with your oncologist or other health care professional.

1. http://www.jnccn.org/content/10/4/545.abstract