Unveiled Findings Reveal Oft-Neglected and Unwelcomed Aspects in Cancer Therapy

Unveiled Findings Reveal Oft-Neglected and Unwelcomed Aspects in Cancer Therapy

The National Council on Radiation Protection and Measurements (NCRP) has published a report on the long-term effects of radiation therapy in cancer treatment, chaired by Lois B. Travis, M.D., Sc.D. [1] The report, which underwent extensive peer review by an outside panel of experts, was made by an expert scientific committee convened by the NCRP.

The report highlights the increased risk of second malignancies (secondary cancers) and cardiovascular disease among cancer survivors. Radiation therapy, a cornerstone of cancer treatment used in approximately 50 percent of all cancer cases, can damage healthy cells along with cancer cells, potentially leading to permanent late effects that manifest months to years after treatment. [2][3]

Second malignancies, typically arising in or near the radiation field, have an approximate risk of around 3%. For example, patients treated with radiation for prostate cancer show a slightly increased risk of bladder or gastrointestinal cancers later on. [3] Such risks depend on the radiation dose, volume of healthy tissue exposed, and patient-specific factors.

Radiation can also adversely affect blood vessels and heart tissue, contributing to long-term cardiovascular complications. This is due to damage such as fibrosis and endarteritis (inflammation and obliteration of small arteries), which may lead to ischemic heart disease or other vascular problems years after treatment.

The NCRP recommends minimizing normal tissue dose via precise radiation delivery, vigilant survivor follow-up, and research into late radiation effects to reduce these long-term risks. The committee emphasizes the need for follow-up studies of cancer survivors, particularly those treated with reduced field sizes and lower dosages. More studies are needed to analyze the relationship between radiation dose and the risk of second malignancies and heart disease. [1]

Additional late effects include fibrosis, hearing loss, osteonecrosis, cataracts, and demyelination, depending on the structures irradiated. For example, radiation to the head and neck may cause hearing loss via damage to cochlear cells and vascular structures in the ear. [1]

The NCRP's role encompasses setting dose limits, promoting research on late effects, and providing guidance for clinicians on managing and mitigating long-term side effects. The Wilmot Cancer Center's Survivorship division is developing a program to provide patients with a comprehensive plan for their post-cancer care. [4]

The number of cancer survivors in the United States has tripled since 1971. As the number of cancer survivors continues to grow, understanding the molecular and genetic underpinnings of radiotherapy-associated late health effects, particularly in patients who develop multiple primary cancers, is crucial. [5]

In conclusion, the long-term side effects of radiation therapy in cancer treatment include an increased risk of second malignancies (~3% risk) and cardiovascular disease due to vascular and tissue damage. The NCRP recommends using precise radiation techniques to limit dose to healthy tissues, careful risk-benefit analysis considering late adverse effects, and lifelong surveillance of cancer survivors for early detection of secondary cancers and cardiovascular complications. [1][2][3][5]

References:

1. National Council on Radiation Protection and Measurements. (2012). Long-term health effects from pediatric and adult exposure to diagnostic radiation: BEIR VII Phase 2. Retrieved from https://www.nap.edu/read/13115/chapter/1
2. National Cancer Institute. (2021). Radiation therapy and second cancers. Retrieved from https://www.cancer.gov/about-cancer/causes-prevention/risk/radiation/radiation-second-cancers-fact-sheet
3. National Cancer Institute. (2021). Radiation therapy and heart disease. Retrieved from https://www.cancer.gov/about-cancer/treatment/types/radiation-therapy/patient/radiation-heart-disease-pdq
4. University of Rochester Medical Center. (2021). Wilmot Cancer Institute's Survivorship division. Retrieved from https://www.urmc.rochester.edu/survivorship/index.aspx
5. American Cancer Society. (2021). Cancer treatment and survival statistics. Retrieved from https://www.cancer.org/research/cancer-facts-statistics/all-cancer-statistics.html
6. The NCRP's report on the long-term effects of radiation therapy in cancer treatment indicates an increased risk of second malignancies (approximately 3%) and cardiovascular disease among cancer survivors, emphasizing the need for research into late radiation effects and more precise radiation delivery methods to reduce these risks.
7. In addition to second malignancies and cardiovascular disease, the long-term side effects of radiation therapy can also include fibrosis, hearing loss, osteonecrosis, cataracts, and demyelination, making it crucial for clinicians to provide comprehensive post-cancer care plans and for the NCRP to continue researching and setting dose limits for radiation therapies and treatments.

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