Pushing for the right radiation therapy treatment
Advances in radiation therapy offer many new treatment choices. When a patient's oncologist recommends radiation, be sure to check into whether the type of radiation the doctor suggests is the most advanced strategy available for his cancer.
Of course, you're naturally going to have many questions. Among them will be concerns about whether the type of radiation the doctor's recommending is the most advanced and aggressive strategy available for the particular type of cancer.
"Not all radiation therapy is created equal" says oncologist Shalom Kalnicki, chairman of radiation oncology at Montefiore Medical Center and the Albert Einstein College of Medicine in New York. "You want to understand what's involved and find out about all the options so you can make the best choice."
For suggestions on what to ask during this important discussion, see 15 Questions to Ask About Radiation Therapy for Breast Cancer . Certainly, the oncologist knows more about cancer than you do and may have solid reasons for recommending a particular treatment -- but it's also possible he's recommending only the treatment available in the hospitals he's affiliated with. To prepare for this talk, you'll want to know the terms for the wide variety of techniques available. Here's a rundown of the newest radiation technologies:
3D-CRT, IMRT, and IG-IMRT (or IGRT) Explained
3-D conformal radiation therapy (3D-CRT)
Probably the most common form of standard radiation used today is conformal radiation, in which doctors use computer technology to map the tumor with imaging techniques such as MRIs and P ET scans. This allows doctors to target the radiation beam to more closely match the shape of the tumor. Scans cover the tumor's width, height, and depth -- hence the term 3-D.
IMRT (intensity-modulated radiation therapy)
IMRT has gradually become the standard of care for certain types of cancers, particularly cancers of the head and neck, lung, abdomen, and pelvis, for which precision in delivering radiation is important. It's also starting to be used in breast and prostate cancer treatment . Here are some basics to know about IMRT:
- It delivers precise, strong radiation. IMRT uses a linear accelerator to deliver thousands of precisely focused small beams of radiation that follow the exact contours of a tumor, allowing the radiation oncologist to target the tumor much more exactly while damaging less of the surrounding tissue. Because surrounding tissue is better protected, the radiation dosages delivered via IMRT can also be higher, resulting in more effective treatment.
"We compared treatment techniques for cancers of the lung, pelvis, abdomen, and head and neck and showed that IMRT was much more effective, and resulted in fewer side effects, than conventional radiation therapy," says Kalnicki, who presented these findings to the American Society for Therapeutic Radiology and Oncology in October 2007.
- It's not available everywhere. Unfortunately, because it uses different equipment than standard radiation therapy, IMRT is not available in all hospitals. If you and the person you're caring for ultimately decide that this is the treatment she wants, she may have to ask her doctor whether she should seek treatment at another hospital or cancer center. It may be worth fighting for, however, as the studies are impressive, and many experts advocate a switch to IMRT for the treatment of many more types of cancer. For example, one recent study of IMRT for prostate cancer -- one of the types of cancer IMRT is not typically used for -- showed that the ability to use higher doses of radiation more than doubled the rate of local tumor control from 43 to 94 percent and reduced the rate of normal tissue damage from 10 to 2 percent.
Image-guided IMRT (IG-IMRT, or IGRT)
- It delivers more easily adjusted radiation. This even more advanced form of IMRT uses online computer imaging to adapt radiation therapy to the changing contours of a tumor in real time during the radiation therapy itself. (In regular IMRT, the mapping is usually done ahead of time.) The computer compares images taken before the procedure to those taken during the procedure itself. Since tumors typically shrink as a result of radiation therapy, IG-IMRT (also called IGRT) allows doctors to adjust the radiation to accommodate the shrinking tumor margins, protecting the growing area of healthy tissue around the edge.
- It's good for delicate locations. Also called image-guided adoptive planning, IG-IMRT has been used with great effectiveness to treat tumors in delicate, complex locations such as the head and neck. Study results show that IG-IMRT allows doctors to use high doses of radiation with less damage to healthy tissue.
Respiratory Gated Radiation Therapy Explained
Another type of IMRT, this technique uses a large linear accelerator inside a doughnut-shaped contraption that spirals around a patient's body during treatment, delivering beams of radiation from many angles. Advocates believe this technique, also called a spiral CT scan, allows even more precisely focused radiation. It's also sometimes used as a screening technique as well.
Respiratory gated radiation therapy
Because radiation therapy requires such precise targeting, even the tiny movements caused by breathing, swallowing, and blood flow can throw off the radiation beams and lead to tissue damage. To solve this problem, respiratory gated treatment employs computer imaging to map radiation treatment so that the dose of radiation is modified to accommodate changes in the shape of the tumor caused by the patient's breathing or swallowing. (Without respiratory gating, doctors typically radiate the entire area that the tumor moves through as the patient breathes, which causes radiation to be delivered to healthy tissue.)
Sometimes called target motion management, this brand-new therapy increases the success of treatment for tumors in the lung, in the breast near the lung or heart, or in the neck or thyroid.
Used almost exclusively for brain tumors, this technique aims a very high-dose radiation beam at a small area during a single session. It's the dramatic procedure you see on hospital shows during which the patient's head is enclosed inside a frame to hold it still. A related technique, stereotactic radiotherapy, uses smaller, fractional doses of radiation given multiple times. It's being studied for potential use on tumors in the lung as well as in the head.