For decades, many patients with hard-to-reach throat cancers received high-dose radiation and chemotherapy, with their often severe toxic effects, because conventional surgery was highly invasive and disfiguring. Now that minimally invasive robotic surgery can be used to resect cancers of the tongue base and tonsils without causing disfigurement, researchers at The University of Texas MD Anderson Cancer Center are learning how this treatment can help minimize the use of radiation and chemotherapy and improve patients’ quality of life.
A changing patient population
The typical characteristics of patients with early-stage tongue base or tonsil cancers have changed substantially in recent decades: patients tend to be younger and more likely to survive the cancer, and their cancers are more likely to be related to human papillomavirus (HPV) rather than tobacco use.
“For younger patients with HPV-related early throat cancers, the prognosis is better out of the gate, so their treatment needs are different,” said Neil Gross, M.D., an associate professor in the Department of Head and Neck Surgery. Because more than 90% of patients with this new profile are expected to survive, head and neck specialists are focusing on developing treatments that have less severe long-term toxic effects.
Drawbacks of open surgery or radiation therapy
The standard treatments for early-stage throat cancer have led to good survival rates, but the resulting quality of life has not been ideal. For a long time, open surgery to remove these cancers—which often involves splitting apart the jaw to gain access—has been almost entirely supplanted by intense radiation combined with cytotoxic chemotherapy. This combination avoids the invasive surgery but can lead to serious long-term toxic effects, including breakdown of the jaw, chronic dry mouth, and dysphagia that can necessitate the placement of a temporary or permanent feeding tube in the stomach. In short, the use of radiation and chemotherapy helps preserve the structures involved but may compromise important speech and swallowing functions and thus diminish quality of life.
“I call this area the ‘kitchen’ of the body because the mouth is where so much happens. It’s involved in social interaction; it’s where you talk, breathe, and eat; it’s where people see you,” Dr. Gross said. “Patients who go through head and neck cancer treatment can have high rates of depression and even suicide because it’s an area that really affects people’s everyday lives.”
Less toxic treatment through surgical technology
The key to minimizing the use of radiation and chemotherapy—and avoiding their toxic effects—in patients with early-stage throat cancers is to increase the use of surgery, but in a minimally invasive form. Today, the da Vinci surgical system for transoral robotic surgery (TORS) allows cancers to be accessed through the mouth rather than through an open approach.
In TORS, head and neck surgeons remotely manipulate flexible robotic arms to control surgical instruments farther back in the throat than is possible with their hands alone. Because surgeons can maneuver the instruments around anatomic structures in the throat, TORS offers an advantage over transoral laser microsurgery, which can be used to perform line-of-sight resections only. In this way, surgeons are able to resect many early-stage tongue base and tonsil tumors with tumor-free margins. For these patients, radiation and/or chemotherapy can be omitted or given at lower, less toxic doses.
“The idea is to remove cancers and either avoid radiation or chemotherapy completely or give a lower dose of radiation or radiation and chemotherapy after surgery in patients who need adjuvant therapy,” Dr. Gross said. He also pointed out that TORS is most effective when performed at high-volume centers by surgeons experienced in the procedure.
Transoral robotic surgery trials
At MD Anderson, clinical trials to evaluate how TORS can be best used to treat tongue base or tonsil cancer and the extent to which the surgery can improve quality of life are under way or on the horizon. In one such ongoing trial, Dr. Gross, Brandon Gunn, M.D., an associate professor in the Department of Radiation Oncology, and their colleagues are investigating ways to track patients’ recovery from either TORS or proton radiation therapy for early-stage, HPV-positive tongue base or tonsil cancer. Because most of these patients can expect a cure, many are particularly concerned about not only survival but also their quality of life and how quickly they can return to normal activities. Thus, the trial will not only assess patient-reported symptoms, such as swallowing ability and fatigue, but also employ wearable activity monitors to gather data on patients’ physical activity, including distances walked, altitude changes, and sleep habits. The trial will help determine whether activity levels measured in this way correlate with the symptoms that patients describe and thus whether data collection with activity monitors can be used in bigger clinical trials that compare quality of life following different treatments.
“Many of these patients are really dragging after treatment, and it takes a long time to recover. Some patients may not get all the way back to normal activity levels,” Dr. Gross said. “And again, these patients tend to be younger, so they tend to be used to busy, active lives. If suddenly they can’t be active, that’s a big change.”
In another trial expected to open at MD Anderson by the middle of this year, patients with tongue base or tonsil cancer will receive an immune checkpoint inhibitor before undergoing TORS. The patients’ initial tumor biopsy specimens, taken before the immunotherapy drug is given, will be compared with their resected tumors to assess the immunotherapy’s biological effects. Moreover, investigators hope to learn whether giving the immunotherapy drug before TORS reduces the need for adjuvant radiation or chemotherapy. Patients with HPV-positive disease and those with HPV-negative disease will be included.
These and other trials will help guide the use of TORS in the multidisciplinary treatment of patients with tongue base and tonsil cancers. As the technology continues to improve and as the instruments become smaller and more agile, TORS may someday be used to resect cancers at even harder-to-reach sites in the throat, including the larynx, trachea, and upper esophagus.
“The technology is catching up with the needs of the kinds of patients we’re seeing today,” Dr. Gross said. “Ultimately, it’s not about the instrument; it’s about the patient.”
For more information, contact Dr. Neil Gross at 713-745-8483.
OncoLog, March 2016, Volume 61, Issue 3