It's quite a challenge to treat severely obese women diagnosed with cervical cancer. Radiation oncologists at an Alabama cancer center described the techniques they have developed to treat such patients, which they believe can be easily replicated at other hospitals, in an article in Practical Radiation Oncology.
It's an understatement to say that cancer patients weighing more than 450 lb have special needs. They need a bariatric-strength table to support their weight when undergoing diagnostic imaging or having radiation therapy. Their weight may exceed the limits of simulation software. Their girth may be in excess of a CT bore or field-of-view, and images may be of poor quality due to tissue attenuation. There may also be issues with patient setup, and verification and achieving an acceptable dose distribution may be difficult (Practical Radiation Oncology, January 9, 2012).
Radiation oncologists at the University of Alabama at Birmingham (UAB) Comprehensive Cancer Center addressed these challenges when two patients in their 30s with stage I cervical cancer were referred to them. One patient weighed 454 lb, and the other weighed 513 lb; both were short in stature, at 5'4" and 5'5", respectively. Because of their size and other medical comorbidities, surgery was not an option for either patient.
Dr. Alexander Whitley, PhD, and colleagues explained what they faced and how they delivered treatment. The hospital had a CT simulator (Brilliance Big Bore, Philips Healthcare) with an 85-cm bore size and a 60-cm scan field-of-view, with a table that could support patients weighing up to 650 lb. The patients' girth resulted in poor-quality images, but they were adequate enough to plan setup based on bony landmarks.
While it was possible to create an accurate body contour for one patient, it was not possible to do so for the other. Instead, the treatment team estimated thickness to calculate the dose algorithm.
The center built a treatment table that consisted of a bariatric-strength stretcher with its cushion removed, supported by Styrofoam blocks that allowed enough room to accommodate portal x-ray imaging. Radiographic images were acquired each day of the anteroposterior and lateral port, with two radiation oncologists reviewing the on-board images. Unique radiation beam designs were developed to prevent unacceptable hot spots near the skin surface.
After radiotherapy treatments had been completed, the patients had a standard prescription dose of 24 Gy in three fractions of intracavitary brachytherapy. Both patients needed to be anesthetized for a portion of this treatment.
More than 67% of the U.S. population is obese, the authors noted, and radiation oncologists will undoubtedly have more severely obese patients as a result. If the experiences of the University of Alabama's radiation oncology department are representative, in addition to preparing a special table and treatment program, departments will need to allocate more time when scheduling these patients for each treatment session and more radiation therapy staff to get them positioned.
