Figure. Comparisons of the number of cases at each T stage (A) and the proportion of patients who died of disease as a function of T stage (B) between the sixth edition1 and seventh edition3 of the American Joint Committee on Cancer's AJCCCancer Staging Manual.
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El-Sawy T, Savar A, Williams MD, De Monte F, Esmaeli B. Prognostic Accuracy of the Seventh Edition vs Sixth Edition of the American Joint Committee on Cancer Tumor Classification for Adenoid Cystic Carcinoma of the Lacrimal Gland. Arch Ophthalmol. 2012;130(5):664–666. doi:10.1001/archophthalmol.2011.1606
In a recent retrospective multicenter analysis, we found that patients with adenoid cystic carcinoma of the lacrimal gland classified as at least T3 according to the criteria in the sixth edition of the American Joint Committee on Cancer's AJCCCancer Staging Manual1 had shorter overall survival and time to metastasis than patients with tumors classified as less than T3.2
Since that publication, the seventh edition of the AJCC Cancer Staging Manual3 has been published with significant differences in the T designation.4 In the sixth edition, tumor size was the primary determinant of T classification; in contrast, in the seventh edition, lacrimal gland carcinomas of any size are classified as T4 if periosteum or bone is involved.
In this study, we compare the prognostic value of the seventh vs sixth edition of the AJCC Cancer Staging Manual for adenoid cystic carcinoma of the lacrimal gland.
Eighteen consecutive patients with adenoid cystic carcinoma of the lacrimal gland treated at MD Anderson Cancer Center from November 1, 1998, to November 1, 2009, were included after appropriate institutional review board approval.
Medical records were reviewed for patient demographic characteristics, treatment details, and clinical features. Each tumor was staged according to the tumor classifications for lacrimal gland carcinoma in both the sixth and seventh editions of the AJCC Cancer Staging Manual. The main outcome measures were local-regional recurrence, distant metastasis, and overall survival and their relationship with tumor classification. Statistical analysis was performed using a 2-sided Fisher exact test.
Patient demographic characteristics, histologic subtype, and TNM designations according to the sixth and seventh editions of the AJCC Cancer Staging Manual are shown in Table 1.
Seventeen of the 18 patients underwent orbital exenteration (16 with bone removal); 1 patient had globe-sparing surgery with removal of the bony walls. All 18 patients received postoperative adjuvant radiation therapy (median dose, 56.6 Gy; to convert to rad, multiply by 100).
The median follow-up time was 49 months (range, 11-161 months). At last follow-up, 10 of the 18 patients (55.6%) were alive with no evidence of disease and 8 (44.4%) had died of their disease.
Application of the seventh edition criteria resulted in a change in TNM designation for 13 of the 18 patients (72.2%) in this series (Table 2). In all cases the upstaging was due to involvement of periosteum or cortical bone. Whereas only 1 of 18 patients (5.6%) had T4 disease according to the sixth edition, 14 of 18 patients (77.8%) had T4 disease according to the seventh edition.
According to the sixth edition, 6 of the 10 patients without distant metastasis (60.0%) had less than T3 disease and none had T4 disease. According to the seventh edition, 8 of the 10 patients without distant metastasis (80.0%) had T4 disease.
Of the 10 patients alive without evidence of disease, 9 (90.0%) had either periosteal or cortical bone involvement, ie, were designated as having T4 disease according to the seventh edition; only 3 of 10 patients alive without evidence of disease (30.0%) had cortical bone involvement. In contrast, 5 of the 8 patients who died of their disease (62.5%) had cortical involvement. However, this difference was not statistically significant (P = .34).
Of the 11 patients with the basaloid subtype, 7 (63.6%) developed metastasis and died of their disease, whereas only 1 of 7 patients (14.3%) with the other histologic subtypes (mixed and cribriform) developed metastasis and died of disease. This difference in prognosis almost reached statistical significance (P = .06).
The AJCC Cancer Staging Manual seventh edition criteria for lacrimal gland carcinoma have placed greater importance on periosteal and cortical bone involvement than tumor size compared with the sixth edition criteria. Our findings indicate that the higher T designations in the seventh edition based on periosteal and bone involvement do not correlate with a greater risk of distant metastasis and tumor-related death for adenoid cystic carcinoma of the lacrimal gland. Our data suggest that the prognostic value of the T designation is lessened when every tumor with periosteal or cortical bone involvement is classified as T4 regardless of size. The upstaging of patients based on periosteal involvement produces the unwanted effect of the large majority—even those who did not develop metastasis and die of their disease—being designated as having T4 disease (Figure).
Basaloid histologic subtype was an adverse histologic feature in our series, correlating with an increased risk of metastasis and death (63.6%) compared with only a 14.3% risk for other histologic subtypes. This difference in prognosis almost reached statistical significance (P = .06); thus, histologic subtype should be considered for inclusion in future editions of AJCC Cancer Staging Manual criteria.
Correspondence: Dr Esmaeli, Section of Ophthalmology, Department of Head and Neck Surgery, University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Unit 1445, Houston, TX 77030 (email@example.com).
Financial Disclosure: None reported.
Funding/Support: This work was supported in part by grant CA016672 to MD Anderson Cancer Center from the National Institutes of Health.
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