Over the past 50 years, there have been incredible changes in the field of colorectal cancer,” Emily K. Bergsland, MD, noted in opening the colorectal cancer session at the Best of ASCO meeting in Chicago. Dr. Bergsland is a gastrointestinal oncologist at the Helen Diller Family Comprehensive Cancer Center and Professor of Clinical Medicine at the University of California, San Francisco.
Evolution of Radiotherapy
Among the changes in radiation oncology, “one very important one relates to the changes in imaging modalities. Fifty years ago, we had very crude ways of assessing tumors,” Dr. Bergsland noted, such as planar images, liver-spleen scans, chest x-rays, and barium enemas. They have been eclipsed first by computed tomography and then by magnetic resonance imaging.
Cobalt, used as an energy source back in the 1960s, “actually had very low penetration and consequently there was a lot of skin toxicity associated with that and poor edge definition, so you got a lot of bleed over into normal tissues,” Dr. Bergsland said. With the linear accelerators now in use, there is minimal skin toxicity, she continued. “You can spare normal tissues, and this has led to techniques such as conformal radiation, intraoperative radiation therapy, and radiosurgery.”
Moving forward, consideration is being given to short-course radiation, possibly over 5 days rather than a traditional 5-week course. “There is also a trend toward looking at which patients might be spared surgery,” Dr. Bergsland said. “There are a lot of questions about whether patients need all three components of therapy, or whether some patients could be spared the surgery, for example, and allow organ preservation, or perhaps they don’t need radiation therapy.”
Whether or not all patients need adjuvant chemotherapy afterward is also being studied. “Everybody is looking to continued advances in molecular profiling to better select our patients.”
Surgical Advances
Turning to advances in surgery, Dr. Bergsland said it was important to remember that “50 years ago, the majority of patients with rectal cancer had a colostomy. Now, in contrast, it is the minority of patients who have a colostomy. There have been significant advances in surgical techniques, including the ability to do a coloanal anastomosis, various new reconstruction techniques, and also techniques involved in dealing with very early-stage rectal cancer,” she said.
Minimally invasive surgery for colon cancer has resulted in reduced trauma and complications and quicker recovery. The data are not as mature for rectal cancer, Dr. Bergsland noted.
Surgical mortality has decreased, “partly due to better perioperative technique and support, and improved anesthesia techniques. With modern- day liver resections, we are looking at perioperative mortalities of only around 1% to 2% in recent studies,” Dr. Bergsland observed.
Future considerations for surgery involve the selection and follow-up of candidates for organ preservation, evolving guidelines for liver resection, and the role of adjuvant/neoadjuvant chemotherapy.
While 50 years ago, chemotherapy basically meant fluorouracil, effective agents now include capecitabine, oxaliplatin, and irinotecan, as well as doublets and triplets. Targeted agents, nonexistent 50 years ago, now include cetuximab (Erbitux), panitumumab (Vectibix), ziv-aflibercept (Zaltrap), bevacizumab (Avastin), and regorafenib (Stivarga). The “one-size-fits-all” approach is giving way to treatment based on molecular classifications. ■
Disclosure: Dr. Bergsland reported no potential conflicts of interest.
