The detection of residual disease after therapy is a particularly difficult problem for patients who have head and neck cancer. Surgery, radiation therapy, and chemotherapy may result in anatomic changes that are difficult to differentiate from recurrent or residual tumor. CT and MRI frequently require serial studies to determine if tumor recurrence is present or absent. FDG-PET is not based on anatomic information, so the functional imaging of PET is not always able to provide an accurate determination of residual disease after therapy. Several studies have demonstrated the sensitivity of PET in the detection of recurrent or residual disease to be 81% to 100%, and the specificity to be 61% to 100%. The lower specificity results from the false-positive studies that occur with inflammatory lesions after radiation therapy, which may persist for up to 4 months after completion of therapy.
Patient studies performed on combined PET/CT fusion scanners are more accurate for the identification of residual disease than studies performed on a PET scanner alone or a CT scanner alone or studies performed on both devices but analyzed together. The determination of an abnormality on a PET scan alone is difficult because of the close proximity of structures in the digestive tract that normally have FDG accumulation, such as tonsillar tissue. Distant metastases are less common than local and regional disease. PET is accurate in the detection of suspected distant metastases in these patients.
Medicare covers PET for diagnosis, staging and restaging of head and neck cancer.
Routine surveillance is not indicated and not recommended by any guidelines. As such, it is not supported by credible scientific evidence published in peer-reviewed medical literature generally and recognized by the relevant medical community, such as guidelines cited in the Reference section.
Per NCCN on p. FOLL-A, “imaging” is recommended within 6 months weeks and thereafter imaging is not routinely recommended for symptomatic patients. There are no prospective data demonstrating a survival benefit for any follow-up strategy in patients with treated head and neck cancer and available retrospective data are conflicting.
There are no prospective data demonstrating a survival benefit for any follow-up strategy in patients with treated head and neck cancer and available retrospective data are conflicting. Routine surveillance has been associated with a survival benefit in some observational studies when patients diagnosed at routine follow-up were compared with those who presented with symptoms . However, other studies have not observed a survival benefit from detecting asymptomatic recurrences. This may be because most recurrences are symptomatic early on or because early diagnosis does not appreciably benefit recurrent patients.
Post-treatment surveillance has been speculated as most likely to be effective in patients who initially have limited disease and who thus retain an option for future curative therapy, such as those with T1 and T2 tumors who received single modality surgery or radiation therapy. Those seem to be the patients who benefit from surveillance in some studies. Despite surveillance, survival remains poor for patients who were previously treated for advanced stage disease or who initially presented with regional disease. NCCN does not recommend surveillance but Nuclear Medicine Society is more supportive, especially after treatment with radiaton.
NCCN, head and neck, 2019
Ezra E. W. Cohen MD Samuel J. LaMonte MD, FACS Nicole L. Erb BA Kerry L. Beckman MPH, CHES Nader Sadeghi MD Katherine A. Hutcheson PhD Michael D. Stubblefield MD Dennis M. Abbott DDS Penelope S. Fisher MS, RN, CORLN Kevin D. Stein PhD Gary H. Lyman MD, MPH, FASCO, FACP Mandi L. PrattChapman MA, American Cancer Society Head and Neck Cancer Survivorship Care Guideline. A Cancer Journal foir CLincials, CA- Cancer Journal for Clinicians Volume66, Issue3 May/June 2016