The Failure Patterns of Oral Cavity Squamous Cell Carcinoma after IntensityModulated Radiotherapy Th

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The Failure Patterns of Oral Cavity Squamous Cell
Carcinoma after Intensity-Modulated Radiotherapy
The University of Iowa Experience

• Min Yao, MD, PhD John E. Bayouth, PhD
• Huaming Tan, MS Judith Wacha, CMD
• Kenneth J. Dornfeld, MD, PhD John M. Buatti, MD

Department of Radiation Oncology University of
Iowa Health Care, Iowa City, Iowa
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Purpose/Objective(s)
It was reported that squamous cell carcinoma of
oral cavity (OCSCC) did worse among head and neck
cancers treated with IMRT. To improve the
treatment outcome, we reviewed our experience in
IMRT treatment of OCSCC.
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Materials/Methods

• From May 2001 to July 2005, 55 patients with
  OCSCC were treated with IMRT for curative intent.
  Patient characteristics summarized in Table 1.
  Stage distribution summarized in Table 1 and
  Table 2.

Table 1. Patient Characteristics
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Table 2. AJCC stage distribution of 55 patients
These patients had lymph node recurrence after
surgical resection of the primary oral cavity
cancer, with no sign of primary recurrence at the
time of treatment.
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Materials/Methods

• Three target volumes CTV1, CTV2 and CTV3 were
  defined. The prescribed doses to CTV1, CTV2, and
  CTV3 in the definitive cohort were 70 Gy, 60 Gy
  and 54 Gy respectively. For high-risk
  postoperative IMRT, the prescribed doses to CTV1,
  CTV2, and CTV3 were 64-66 Gy, 60 Gy and 54 Gy
  respectively. For intermediate-risk postoperative
  IMRT, the prescribed doses to CTV1, CTV2 and CTV3
  were 60 Gy, 60 Gy and 54 Gy.

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Materials/Methods
The failure patterns were determined by
co-registration or comparison of the treatment
planning CT to the CT, PET-CT, or MRI obtained
at the time of recurrence.
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Results

• The median follow-up for all patients was 17.1
  months (range, 0.27 - 59.3 months). The median
  follow-up for living patients was 23.9 months
  (range, 9.3 - 59.3 months). There were 9 patients
  with local-regional failures 4 local failures
  only, 2 regional failures only, and 3 had both
  local and regional failures. There were 5
  patients failed distantly 3 of them also had
  loco-regional failures.

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Results

• The 2-year overall survival, disease-specific
  survival, local recurrence free survival,
  loco-regional recurrence free survival, and
  distant disease free survival is 68, 74, 85,
  82 and 89, respectively. Fig 1 5.

Figure 2
Figure 1
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Figure 4
Figure 3
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Figure 5
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Results

• The median time from treatment completion to
  local-regional recurrence was 4.1 months (range,
  3.0 to 12.1 months). Except one patient who
  failed in contralateral lower neck that was
  outside the radiation field, all failed in the
  areas that had received a high dose of radiation.
  Failure patterns are summarized in Table 3 and
  illustrated in Fig. 6 and Fig. 7.

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Table 3. Clinical characteristics and patterns of
locoregional failures
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Stage T4N1 left retramolar trigone cancer treated
with postoperative IMRT (patient 8). A.
Composite treatment plan. B. PET-CT obtained 14
weeks post-radiation revealed increased FDG
uptake focus in the masticator space,
corresponding to a mass lesion. CT guided FNA
revealed SCC. Visual comparison of A and B
reveals the recurrent tumor is within the region
that received a high dose of radiation.
Figure 6
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Stage T4N2C left oral tongue cancer received
postoperative IMRT (patient 4). A. Treatment
plan. B. Co-registration of treatment planning
CT (Panel A) to the diagnostic CT at the time of
detection of recurrent tumor. This shows that
part of the recurrent tumor is within PTV1, and
part of it is outside PTV1 but within PTV2, that
was irradiated to 60 Gy.
Figure 7
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Results
The local regional control is strongly correlated
with extracapsular extension (ECE) Fig 8. It is
also correlated with the subsite of the tumor.
Fig.9.
Figure 8
Figure 9
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Conclusions

• IMRT is effective for oral cavity squamous cell
  carcinoma
• Most failures are in field failures
• For patients with extracapsular extension,
  postoperative radiation with concurrent
  chemotherapy is recommended.