• Explain to interested patients that patients who have head and neck cancer often fail to complete radiotherapy without interruption.
• Note that patients who have surgery are more likely to complete the course of radiation and those who undergo chemotherapy and radiotherapy simultaneously are less likely to do so.

Nearly 40% of Medicare patients with head and neck cancer stop radiation therapy early, although those who’ve had surgery are more likely to finish the treatment, researchers found.

Among patients with all types of head and neck cancer, 70% who underwent surgery completed radiotherapy with no interruptions compared with only 52% of nonsurgical patients (P<0.001), according to the study published in the Sept. 21 issue of the Archives of Otolaryngology-Head & Neck Surgery.

Those who underwent concurrent chemotherapy or suffered from other illnesses were also less likely to complete radiotherapy, according to Scott D. Ramsey, MD, PhD, of the Fred Hutchinson Cancer Research Center in Seattle, and colleagues.

The higher percentage for surgical patients “likely reflects selection of patients for surgery who are more likely to complete therapy because of clinical and other patient-specific factors,” they wrote.

Head and neck cancers account for 6% of all malignancies in the U.S., according to the National Cancer Institute.

Radiotherapy, delivered alone or as an adjuvant to surgery or chemotherapy, can be an effective treatment for these cancers, and clinical evidence suggests that the radiation dose and duration of treatment is correlated with tumor control and survival.

But, radiotherapy can have side effects — painful inflammation and ulceration of the mucous membranes lining the digestive tract, dry mouth, difficulty swallowing, and aspiration — causing patients to stop treatment.

Breaks in radiotherapy treatment have been shown to result in poor tumor control in the larynx, pharynx, and oral cavity, the researchers noted, but “the incidence of incomplete and/or interrupted radiotherapy, as well as factors that put patients at risk of not completing therapy, has not been studied in a large, population-based sample,” the researchers said.

To address this knowledge gap, the authors analyzed data on 5,086 Medicare patients who were diagnosed with head and neck cancer between 1997 and 2003. The data came from the National Cancer Institute’s Surveillance, Epidemiology, and End Results database, a cancer registry linked to Medicare records.

Overall, 14.8% of patients had chemotherapy in addition to radiotherapy. Of the surgical patients, 63.3% had the procedure 30 days or more before starting radiation.

Even among those who had surgery, likelihood of finishing radiation treatment varied with tumor site. Among those who underwent surgery within 30 days before beginning radiation:

• Patients with oral cavity tumors were 2.43 times more likely to complete planned therapy (95% CI 1.69 to 3.48)
• Those with pharyngeal tumors were 2.05 times more likely (95% CI 1.27 to 3.29)
• Patients with laryngeal tumors were 2.91 times more likely (95% CI 2.16 to 3.91)
• Those with nasal tumors were 3.59 times more likely (95% CI 1.94 to 6.65)
• Those with salivary gland tumors were 7.16 times more to complete treatment (95% CI 3.22 to 15.94)

Comorbidities, as measured by the Charlson Comorbidity Index, also decreased the likelihood of completing therapy, as did metastases.

Of the surgical patients, 72% of those who received only radiation as an adjuvant treatment had no interruption in radiotherapy, compared with only 50% of those who received radiation and chemotherapy simultaneously.

The authors theorized that toxic effects of chemotherapy agents might cause patients to take extended breaks between therapies, disrupting planned radiotherapy treatment schedules.

The researchers offered several reasons why surgical patients were more likely to complete radiotherapy. “First, characteristics that make patients good candidates for surgery may also make them more likely to complete radiotherapy,” they wrote. “Because comorbidities are known to decrease survival in patients with head and neck cancer, healthier patients may be chosen by surgeons to complete more rigorous treatments (e.g., surgery in addition to radiotherapy). In addition, patients who are willing to undergo major surgery to treat their disease may also be more motivated to complete a full course of uninterrupted radiation therapy, despite any toxic effects of treatment that may occur.”

They cautioned that the study was observational and retrospective and thus the data were limited in accuracy and scope. Information was spotty or nonexistent on radiation doses, therapeutic versus palliative care, and patients’ quality of life and ability to function during the study period.

They also noted that sample sizes for some combinations of tumor sites and stage may have prevented them from detecting statistically significant survival differences.

“Because chemotherapy appears to reduce the likelihood of completing radiotherapy,” they concluded, “future research is needed to identify specific agents, doses, and schedules that specifically reduce the likelihood of completing treatment in community settings.”