Patterns of Disease Recurrence Following Treatment of Oropharyngeal Cancer With Intensity Modulated Radiation Therapy

doi:10.1016/j.ijrobp.2012.08.004

International Journal of Radiation OncologyBiologyPhysics

Volume 85, Issue 4, 15 March 2013, Pages 941-947

https://doi.org/10.1016/j.ijrobp.2012.08.004 Get rights and content

Purpose

To report mature results of a large cohort of patients diagnosed with squamous cell carcinoma of the oropharynx who were treated with intensity modulated radiation therapy (IMRT).

Methods and Materials

The database of patients irradiated at The University of Texas, M.D. Anderson Cancer Center was searched for patients diagnosed with oropharyngeal cancer and treated with IMRT between 2000 and 2007. A retrospective review of outcome data was performed.

Results

The cohort consisted of 776 patients. One hundred fifty-nine patients (21%) were current smokers, 279 (36%) former smokers, and 337 (43%) never smokers. T and N categories and American Joint Committee on Cancer group stages were distributed as follows: T1/x, 288 (37%); T2, 288 (37%); T3, 113 (15%); T4, 87 (11%); N0, 88(12%); N1/x, 140 (18%); N2a, 101 (13%); N2b, 269 (35%); N2c, 122 (16%); and N3, 56 (7%); stage I, 18(2%); stage II, 40(5%); stage III, 150(19%); and stage IV, 568(74%). Seventy-one patients (10%) presented with nodes in level IV. Median follow-up was 54 months. The 5-year overall survival, locoregional control, and overall recurrence-free survival rates were 84%, 90%, and 82%, respectively. Primary site recurrence developed in 7% of patients, and neck recurrence with primary site control in 3%. We could only identify 12 patients (2%) who had locoregional recurrence outside the high-dose target volumes. Poorer survival rates were observed in current smokers, patients with larger primary (T) tumors and lower neck disease.

Conclusions

Patients with oropharyngeal cancer treated with IMRT have excellent disease control. Locoregional recurrence was uncommon, and most often occurred in the high dose volumes. Parotid sparing was accomplished in nearly all patients without compromising tumor coverage.

Introduction

During the past decade, intensity modulated radiation therapy (IMRT) has evolved from a novel form of conformal therapy to be used in complicated cases of head-and-neck cancer to the standard method of radiation treatment planning and delivery. Studies have documented the rapid rise in the use of IMRT in the United States for the treatment of head-and-neck cancer (1) and numerous authors have described experiences of IMRT in the treatment of head-and-neck cancer 2, 3, 4, 5. The initial favorable outcomes with IMRT led the Radiation Therapy Oncology Group (RTOG) to initiate 2 trials testing the feasibility of IMRT in the multi-institutional setting 6, 7. Since the success of these 2 trials, the RTOG and other cooperative groups have allowed the use of IMRT in their head-and-neck trials.

The appeal of IMRT in the treatment of oropharynx cancer is principally the ability to lower doses to the parotid glands and minimize the incidence of severe xerostomia. Initial studies suggested reducing the dose to a parotid gland below 26 Gy will result in significant reduction in xerostomia (8), and this dose remains the goal set for dosing to the parotid glands when using IMRT. Other studies have demonstrated that there is not an absolute threshold dose, and doses below 40 Gy to the parotid result in varying reduction of the risk of xerostomia. Eisbruch et al and Nutting et al have recently reported 2 separate multi-institutional trials demonstrating that IMRT can reduce the incidence and severity of xerostomia for patients with oropharyngeal cancer 6, 9.

Our early efforts focused on patients with small primary tumors often treated with radiation alone (3). Since 2003, IMRT has been our routine form of radiation planning and delivery for the treatment of patients with oropharyngeal cancer. This current study expands our previous report with a much larger cohort and longer follow-up with the focus on patterns of recurrence. Specifically, we were interested in identifying the sites of local and regional recurrences in relationship to the doses of radiation that were delivered conformally to clinical and subclinical target volumes.

Section snippets

Methods and Materials

The database maintained by the Department of Radiation Oncology at The University of Texas MD Anderson Cancer Center (MDACC) was searched to identify patients irradiated with IMRT for oropharyngeal carcinoma (squamous cell, undifferentiated, or not otherwise specified) between the years 2000-2007. Our institutional review board granted permission to conduct this retrospective study.

The search identified 827 medical records. Patients were excluded for the following reasons: distant metastases or

Patients and staging

Table 1A, Table 1B details the demographics of the cohort. The patients were predominantly male with a median age of 55 years old (range 28-84). Five hundred seventy-six patients (74%) had T1-2 disease, but as only 88 (12%) were node negative, 93% had stage III and IV disease.

Surgery

One hundred twenty-five patients (16%) had tonsillectomies, principally as a diagnostic procedure. Five patients had an excision of their primary tumor. One patient had a partial glossectomy and 1 patient had a composite

Survival

The median follow-up for all patients was 54 months (range 1-120 months). The actuarial 2- and 5-year overall survival rates were 93% and 84%, respectively (Figure 1). Increasing T-category current smoking, and non-tonsil/base of tongue tumors were associated with poorer survival (P<.001 for all 3 variables). Group staging was also significantly associated with survival (P<.01). Node positivity was not associated with poorer survival (P=.25), though N-category was significant as patients with

Discussion

Our current study describes a large cohort of patients with oropharyngeal carcinoma treated with IMRT. Disease recurrence in the primary tumor site or regional lymphatics was uncommon, as the 5 year locoregional control rate was 90%. Disease control and survival was associated with smoking status and tumor subsite within the oropharynx. This is consistent with known data regarding a more favorable prognosis with human papillomavirus- associated tumors, which more commonly develop among

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Clinical InvestigationPatterns of Disease Recurrence Following Treatment of Oropharyngeal Cancer With Intensity Modulated Radiation Therapy

Purpose

Methods and Materials

Results

Conclusions

Introduction

Section snippets

Methods and Materials

Patients and staging

Surgery

Survival

Discussion

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Lancet Oncol

Int J Radiat Oncol Biol Phys

Radiotherapy Oncology

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Evaluation of trends in the use of intensity-modulated radiotherapy for head and neck cancer from 2000 through 2005: Socioeconomic disparity and geographic variation in a large population-based cohort

Cancer

Clinical Investigation
Patterns of Disease Recurrence Following Treatment of Oropharyngeal Cancer With Intensity Modulated Radiation Therapy