Menu
Menu
CRC Radiation
Home /
CRC Radiation
Colorectal
Radiation Therapy
Radiation therapy is often used in the treatment of colorectal cancer. The decision on the use of radiation therapy depends on the type and stage of the cancer being treated with its most prevalent use in patients with Stage II and Stage III colorectal cancer. Radiation therapy can be used either in a pre-operative (neoadjuvant), intraoperative, post-operative (adjuvant) or palliative setting. It is occasionally also used as the primary treatment if a patient has inoperable localized disease.
When radiation is used prior to surgery to shrink the tumor so that it is easier to remove, it is called neoadjuvant therapy. While neoadjuvant radiation therapy is not widely used, recent studies have reported that its use may can result in tumor downstaging, high cure or complete remission rates (R0 resection rates), and improved overall survival.1
When intraoperative radiation therapy (IORT) is delivered during surgery, it enables direct radiation of any potential cancer cells near where the tumor was removed and avoidance of irradiating normal tissue in the area near the tumor.
The use of radiation following surgery to treat residual cancer cells not removed during surgery is called adjuvant therapy. Colorectal cancer diagnosed and treated surgically at an earlier stage is associated with a lower risk of recurrence. A recent study reported that 16% of patient diagnosed with colorectal cancer had recurrences within 40 months following surgery with a median time to recurrence of 14 months.2
Types of radiation therapy
- External-beam radiation therapy – External-beam radiation therapy deliver x-rays to where the cancer is located. How many times and how long a patient received radiation treatment is dependent on the purpose of the radiation therapy and other clinical factors. This could be for a few days or for several weeks. There are several newer types of external-beam radiation used to treat colorectal cancer that has metastasized or spread to the lungs or liver. This includes intensity modulated radiation therapy (IMRT), three-dimensional conformal radiation therapy (3D-CRT), and stereotactic body radiation therapy (SBRT). These radiation therapy options have increased accuracy compared to standard external-beam radiation and can limit radiation exposure to healthy tissue near the site of the tumor(s).
- Intraoperative radiation therapy – Intraoperative radiation therapy uses a single, high dose of radiation therapy to the area the tumor was removed during surgery.
- Brachytherapy – Brachytherapy is a treatment where radioactive material placed inside a seed, pellet, wire, or capsule is implanted in near the tumor using a needle or catheter inserted into a blood vessel. The radiation damages the DNA of nearby cancer cells.
Advertisement
Chemoradiation therapy
Sometimes chemotherapy is used in conjunction with radiation in the above settings. 
This combined use is called chemoradiation therapy (CRT). CRT can enable synergistic antitumor effects from the combination of both treatment modalities and has been shown to improve patient survival and local disease control without significant long-term toxicities in patients with locally advanced solid tumors including gastrointestinal malignancies.
CRT has also been used to shrink tumors when given in a neoadjuvant setting, increasing the possibility of enabling curative surgical interventions in patient’s tumors previously deemed unresectable.3  With the availabilty of newer immunotherapy drugs including immune checkpoint inhibitors, the combination of these agents with radiation is an increasing area for research.4Â
- Qaderi SM, Galjart B, Verhoef C, Slooter GD, Koopman M, Verhoeven RHA, de Wilt JHW, van Erning FN. Disease recurrence after colorectal cancer surgery in the modern era: a population-based study. Int J Colorectal Dis. 2021 Nov;36(11):2399-2410. doi: 10.1007/s00384-021-03914-w.
- Vogel JD, Felder SI, Bhama AR, et al. The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Management of Colon Cancer. Dis Colon Rectum. 2022 Feb 1;65(2):148-177. doi: 10.1097/DCR.0000000000002323.
- Rallis KS, Lai Yau TH, Sideris M. Chemoradiotherapy in Cancer Treatment: Rationale and Clinical Applications. Anticancer Res. 2021 Jan;41(1):1-7. doi: 10.21873/anticanres.14746.
- Wahl DR, Lawrence TS. Integrating chemoradiation and molecularly targeted therapy. Adv Drug Deliv Rev. 2017 Jan 15;109:74-83. doi: 10.1016/j.addr.2015.11.007.
