Due to lower birth rates and better healthcare, the average age of the world's population has increased. In Korea in particular, rapid increases in life expectancy have been observed over the past few decades, with the life expectancy of females increasing from 79.6 years in 2000 to 85.1 years in 2013 (1). This increase in life expectancy is closely related in the case of various cancers, since about 60% of all tumors arise in patients who are older than 65 years. Furthermore, 70% of all deaths due to cancer occur in elderly patients (234). Although the majority of cases with head and neck cancer (HNC) occur between the fifth and sixth decade of life, the onset of the disease in patients older than 60 years is common (4), with up to 24% of HNC cases diagnosed in patients older than 70 years (23). Due to the increase in life expectancies as well as the improvements in global cancer care and survival rates, the traditional age limit of 65 years used by the European Organization for Research and Treatment of Cancer (EORTC) has been challenged in recent years. Moreover, sub-categories of "younger old" (65-70 years old) and "older old" (> 80 years old) have been introduced to allow for the allocation of elderly patients with cancer to homogenous patient groups (5).

Because of the complexity of the anatomy and function of head and neck region and aggressive features of tumor arising head and neck area, the treatment of HNC is often associated with high morbidity and mortality rates. In general, it is common for elderly patients to display poor physical functions and poor social support. Also, elderly patients with HNC tend to display numbers of comorbidities. As the number of elderly patients with HNC increases, head and neck surgeons are increasingly faced with a therapeutic dilemma.

In fact, several studies indicate that older patients with HNC are less likely to receive curative treatment compared to their younger counterparts (6789). However, a number of recent studies have shown that radical surgical or radiotherapy treatment can be performed safely in elderly patients without an increase in overall complication rates, provided that the patients do not have severe comorbidities; these findings have led to a number of debates (678). In a study evaluating HNC patients who were 80 years of age or older, Italiano et al. (10) reported that, despite their age, overall survival was similar to the actuarial survival for general octogenarian populations, and that there was no significant difference in the frequency of preoperative and postoperative complications compared to younger patients (aged 65 years or younger). Indeed, as has previously been suggested (41112), chronological age alone should not be a contraindication to an aggressive surgical approach, which should be attempted whenever the risk assessment ratio is favorable.

It is hard to make a decision of age cutoff to treat radically in HNC patients. In this study, we aim to know which the chronological age would be cutoff to treat HNC comparing septuagenarians and octogenarians by reviewing our treatment strategies for elderly patients with HNC. We also analyzed the effect of age on the choice of initial treatment and compliance to treatment of HNC patients. We also reviewed our experience with older old patients (octogenarians) with HNC.

We performed a retrospective analysis of 260 HNC patients aged 70 years or older at the first diagnosis between 2000 and 2012. Patients who had thyroid cancer and lymphoma were excluded. Patients were divided into 3 groups according to age: group 1 consisted of patients of ages between 70 and 74 years; group 2 consisted of those aged between 75 and 79 years; and group 3 consisted of those who were 80 years of age or older. The follow-up period ranged from 0 to 133.5 months, with a median follow-up period of 29.4 months.
 Demographic data such as age, sex, location of primary tumor, pathology, and TNM staging were reviewed, in addition to data regarding treatment modalities, treatment compliance, and outcome of treatment (overall survival).
 In order to assess the effect of comorbidities on elderly patients, we examined various indices for the general condition of elderly patients using the Adult Comorbidity Evaluation (ACE)-27 (13) and the American Society of Anesthesiologists' (ASA) risk classification system. ACE-27 provides a comprehensive review of the condition of the cardiovascular, gastro-intestinal, renal, endocrine, neurological, psychiatric, rheumatologic, and immunological systems, as well as body weight and any reported malignancies or substance abuse. Each category contains 3 grades (1, mild; 2, moderate; and 3, severe), with the overall comorbidity score defined according to the highest ranked single disease. Two or more grade 2 ailments occurring in different organ systems indicate a classification of grade 3. ACE-27 grades were allotted as 0, 1, 2, or 3 in the hospital information system. A complete ACE-27 data form is available on http://oto.wustl.edu/clinepi/calc.html (Clinical Outcomes Research Office's Website) (14). ACE-27 has been widely validated for HNC (13).
The ASA class of the patient was obtained from the original anesthesia form assigned by the attending anesthesiologist. The latter is an index for perioperative risk; however, it can also be used to evaluate comorbidity as it describes the patient's physical status prior to surgery (15). ASA classifications are as follows: class 1, a normal healthy patient; class 2, a patient with mild systemic disease; class 3, a patient with severe systemic disease; class 4, a patient with disease that is a constant threat to life; class 5, a moribund patient who is not expected to survive without surgery; and class 6, a brain-dead patient (14). 
 Demographic data were subjected to univariate analysis using Fischer's exact or χ² tests, and the Mann-Whitney rank sum test. For statistical analysis, a P value less than 0.05 was considered significant. Kaplan-Meier estimates of the cumulative probability of overall survival were obtained. All statistical analyses were conducted using the SPSS software, version 18.0 (SPSS Inc., Chicago, IL, USA)

It has been reported that HNC often displays aggressive progression and poor prognosis. Treatment decisions for HNC patients are complicated by the fact that the head and neck area is anatomically complex and plays vital physiological roles. From our review of the case history of elderly patients with HNC, we found that the majority of these patients presented with one or more comorbidities that affected the choice of the treatment modality. In general, surgery, RT, and CCRT have long been the major treatment approaches for advanced HNC. However, the management of HNC in a geriatric group is far more complex due to the high toxicity of loco-regional treatments and the high risk of functional deterioration in elderly HNC patients with a high comorbidity burden and impaired functional status (17). For these reasons, the treatment for HNC of elderly patients represents a global health challenge. 
 Several studies have reported on the treatment of the geriatric population, with variable age limits. First, it is important to clarify what defines a person as "elderly." This definition has been modified in recent years due to the increasing global life expectancy. In 2014, the life expectancy of Korean females was over 80 years old at birth, and the mean age of our study group was 76.9 years. The classical definition of an elderly person originally referred to individuals who were at least 65 years of age in 1998, and this definition was used by the EORTC in clinical trials of radical RT to treat HNC (18). However, at present, an age of 65 years is no longer considered to describe an individual as "elderly". There have been many studies about geriatrics, and the definition of "elderly" was variable. Because of differences in efficacy of treatment such as altered pharmacokinetics and dynamics are observed after that age (19), age 70 is a reference point commonly used in clinical trials in oncology (20). We defined "elderly" patients were aged ≥ 70 years at the time of diagnosis, and we sub-divided elderly patients into 3 groups to find any clinical differences between them; age ranged from 70 to 74, 75 to 79, and ≥ 80 years.

In our study groups, the most prevalent primary tumor site was the oral cavity and the larynx, followed by the oropharynx, and hypopharynx. It was concordant with a study of HNC patients who were at least 80 years old (10). While reviewing our groups, there were significant differences of general conditions scaling by ACE-27 and ASA between their seventies and eighties or over.

In patients aged over 80 years old, the compliance of treatment was also significantly decreased. Among the patients who started to treat their HNC, the preference for surgery was dramatically decreased in group 3, which was consistent with previous studies of older HNC patients either surgery alone (21) or in combination with RT or CCRT (11). In contrast, RT was the most preferred in group 3. RT was thought to show lower toxicity than chemotherapy and thus, RT would be considered as an attractive curative option (alone or with systemic therapy) for elderly patients who refused to undergo surgery due to their frailty. It was supported by several studies which have described RT as a safe and effective treatment for HNC even in elderly patients (62223). In addition to the difficulties in terms of the choice of treatment modality for HNC, treatment compliance can also be problematic in elderly patients, due to several factors including progressive loss of stress tolerance, decline in functional reserve of multiple organ systems, high prevalence of comorbid conditions, limited socioeconomic support, reduced cognition, and higher prevalence of depression (24). Although preference of RT as an initial treatment for HNC was high in elderly patients, compliance to RT was poor in our study groups. Even over half of patients who agreed to receive RT eventually discontinuing treatment. This finding is consistent with a recent study, which reported a treatment compliance of approximately 60% for both radical and palliative purposes in elderly patients (24). Since elderly patients had to receive RT 5 times per week, for several weeks in an outpatient clinic in Korea, such prolonged treatment can be an important cause of low compliance with RT.

Meanwhile, many studies have suggested that chronological age alone should not be a contraindication to an aggressive surgical approach and it should be attempted whenever risk-assessment ration is favorable (41112). In addition to aggressive radical surgery, microvascular reconstruction in the elderly can be performed with high success rates even in the octogenarian group (25). In our study, radical surgery such as maxillectomy, mandibulectomy, or laryngectomy and even free microvascular reconstruction were reportedly successfully performed in octogenarian patients. Despite the fact that the latter patients displayed at least 2 comorbidities, they showed no significant postoperative complications associated with these radical surgeries.

The limitation of this study lies in the fact that the analysis was retrospective and represented the case histories of a relatively small number of patients. In addition, our study groups were so heterogeneous to reveal survival differences due to including all types of HNC. However, the incidence of HNC is relatively lower than other malignancies and even elderly patients of HNC are rare. For those reasons, our study has meaning that we can overview the results of treatment and compliances of treatment in elderly HNC patients. Moreover, our study focused on an Asian population, which has shown rapid increases in life expectancy over the past several decades, contrast to previous large-scale studies in Western countries. Previous studies had shown various limitations in the treatment of elderly HNC patients. In our study, we divided a cohort of elderly patients into several groups, and analyzed the difference between elderly patients and older old patients. No significant differences were presented between the age groups; however, the tumor stage at the first diagnosis became more advanced as age increased. There were no significant differences in comorbidities between patients aged between 70 and 75 years and those aged between 76 and 80 years. However, octogenarians had significantly more comorbidities than septuagenarians.

With regard to care for patients with HNC, octogenarians should receive special attention because they have more comorbidities than septuagenarians. Despite being octogenarians and having several comorbidities, most of these patients were treated with surgical procedures without significant complications. RT is preferred to various other treatment modalities, and yields several advantages for elderly patients. Considering the low compliance of patients to RT and its prolonged treatment duration, surgery for octogenarians would be an excellent treatment option whenever the risk assessment ratio is determined to be favorable.