Oral Cavity Squamous Cell Carcinomas in Patients with a History of Oral Lichen Planus: Frequency and Outcomes

PURPOSE/OBJECTIVE(S)

Oral lichen planus (OLP) is an inflammatory condition which affects the mucous membranes of the oral cavity. While previous studies have described the association between OLP and development of oral cavity cancer, there is currently a paucity of literature examining the impact of this disease on treatment response and prognosis. As such, we present a retrospective cohort study of Oral cavity squamous cell carcinoma (OCSCC) patients with a history of OLP to explore the course of their disease.

MATERIALS/METHODS

Using an IRB approved tertiary care registry of head and neck cancer patients, we identified patients with OCSCC who had a prior diagnosis of OLP. The number of new primary tumors, rates of local (LF), regional (RF) and distant failure (DF), as well as overall survival (OS) were assessed using Cox proportional hazards and Kaplan Meier analysis for actuarial survival estimates.

RESULTS

Fifty-four patients with OCSCC and OLP were identified with 109 individual OCSCC diagnoses. Patients had a median age of 67 years, were predominantly female (n = 42, 77.8%) and never smokers (n = 29, 53.7%) with a median follow up after diagnosis of OCSCC of 46.5 months. Nine patients (16.7%) had a history of immunosuppression of whom 6 (11.1%) had chronic steroid use for treatment of OLP. Within the cohort, 33 (61.1%) of OLP patients had a single OCSCC, 11 (20.4%) had 2, and 10 (18.5%) had >3 separate tumors develop. The most common oral cavity subsites were oral tongue (n = 42, 38.5%), followed by alveolar ridge (n = 14, 12.8%) and gingiva (n = 13, 11.9%). Papillary SCC subtype was identified in 10.1%. 92.7% of tumors (n = 101) were treated with primary surgery, with 23 (21.1%) receiving adjuvant RT and 10 of those patients receiving concurrent chemotherapy. Among resected patients, pathologic stages were predominantly T1-2 (84.1%) and N0 (50% vs N1 15.6% and N2a-3 34.4%). The mean RT dose was 62 Gy in 32 fractions. Locoregional failure occurred in 24.8% of cancers (n = 27), with local and regional failure occurring in 13.8% (n = 15) and 11% (n = 12) of lesions, respectively. Recurrence free survival at 3 and 5 years was 75% and 70.3%, respectively, with overall survival at 3 and 5 years of 71.1% and 67%, respectively.

CONCLUSION

Patients with OCSCC and a history of OLP are predominantly female and never smokers. The tumors that develop in such patients are often early stage but a proportion of patients appear to be at higher risk of developing multiple malignancies and surveillance of this patient population to identify new tumors is crucial.

Partial Tongue Sparing without Marginal Failures: The Dosimetric Advantages for Oral Tongue Squamous Cell Carcinoma

PURPOSE/OBJECTIVE(S)

Due to a lack of internal barriers, many radiation oncologists believe whole tongue (WT) irradiation is warranted in the adjuvant setting for oral tongue cancer. Our institutional practice is to include the resection bed and flap with a 5-10 mm margin, attempting to spare unaffected oral tongue. We hypothesize that partial tongue (PT) irradiation, when feasible, results in decreased dose to surrounding normal structures without an increased risk of local recurrence (LR).

MATERIALS/METHODS

Patients with a new diagnosis of squamous cell carcinoma of the oral tongue treated with adjuvant IMRT between 2010 and 2021 were collected from an IRB approved database. PT was defined as <80% of residual tongue in the clinical target volume (CTV). Recurrence was deemed local if in the tongue or floor of mouth, and in field if within the CTV or marginal if outside of CTV. Mean dose to mandible, pharyngeal constrictors, and oral cavity were evaluated. Comparisons between groups were made using parametric one-way ANOVA. Multivariable linear regression was used to predict mean radiation dose. Local control and overall survival were estimated using Kaplan-Meier.

RESULTS

A total of 130 patients are included with median follow up 34.1 months (IQR 13.5-64.6). Radiation dose was 48-72 Gy in 24-36 fractions, most commonly 60-66 Gy in 30-33 fractions (84.6%). All were treated to oral cavity, and neck irradiation included bilateral 96 (72%), unilateral 31 (24%), and none 3 (4%). PT sparing was feasible in 91 (70%) and 39 (30%) required WT. Primary tumor stage in PT included 20 pT1, 50 pT2, 17 pT3, and 4 pT4, and WT included 3 pT1, 8 pT2, 15 pT3, and 13 pT4. 3-year local control for PT and WT was 96% and 87%, respectively. LR occurred in 14 patients overall (10.8%), 6.6% (6) of patients treated with PT and 20.5% (8) treated with WT (p = 0.072). Of the LR for PT, stage was 2 pT1, 3 pT2, and 1 pT3, and all occurred within the radiation field. Of the LR for WT, stage was 1 each of pT1 and pT2, 2 pT3, and 4 pT4. Overall survival was 57%, regional and distant recurrence was each 17.7%. Dosimetric analysis for PT vs WT is described in Table 1, demonstrating lower mean dose when the primary tumor CTV is limited to PT. Unilateral neck irradiation also resulted in a lower mandible [-8.5 Gy (-11.2 - -5.8)], pharyngeal constrictor [-14.3 Gy (-18.1 - -10.5)], and oral cavity [-9.0 Gy (-13.0 - -5.0)] dose (all p<0.001).

CONCLUSION

Limiting the primary tumor CTV to PT for adjuvant radiotherapy resulted in significant sparing of the mandible and pharyngeal constrictors, and a routinely lower oral cavity mean dose of ≥3.5 Gy. There was a low risk of LR when implementing PT, and all LR occurred in field. Given the increased sparing of normal structures, and low risk of LR outside of PT radiation field, sparing a portion of unaffected oral tongue should be considered.

Verification of aquatic dilution factors for liquid effluents released from a nuclear power plant

Dilution factors for liquid effluents released from the Fermi 2 Power Plant into Lake Erie were verified using updated liquid effluent release data, and currently available aquatic dispersion models. A near-field dilution factor of 5 currently used by Fermi 2 appears to be a reasonable assumption as supported by two models and site-specific data. Previously assumed dilution factors for shoreline points outside the near field are of the same order of magnitude as those calculated by this study. The dilution factor of 77, currently used by Fermi 2, at the Monroe water intake point is very conservative when compared with values calculated by this study. More accurate values could be generated by tracer studies as recommended by Regulatory Guide 1.113. Such studies can predict plume behavior and are more accurate than aquatic models. These new values would probably be less conservative than those currently in use, and their use would make it less likely that Fermi 2 will reach technical specification limits for liquid effluent dose.

A monoclonal antibody to (S)-abscisic acid: its characterisation and use in a radioimmunoassay for measuring abscisic acid in crude extracts of cereal and lupin leaves

A monoclonal antibody produced to abscisic acid (ABA) has been characterised and the development of a radioimmunoassay (RIA) for ABA using the antibody is described. The antibody had a high selectivity for the free acid of (S)-cis, trans-ABA. Using the antibody, ABA could be assayed reliably in the RIA over a range from 100 to 4000 pg (0.4 to 15 pmol) ABA per assay vial. As methanol and acetone affected ABA-antibody binding, water was used to extract ABA from leaves. Water was as effective as aqueous methanol and acetone in extracting the ABA present. Crude aqueous extracts of wheat, maize and lupin leaves could be analysed without serious interference from other immunoreactive material. This was shown by measuring the distribution of immunoreactivity in crude extracts separated by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), or by comparing the assay with physicochemical methods of analysis. Analysis of crude extracts by RIA and either, after TLC purification, by gas chromatography using an electron-capture detector or, after HPLC purification, by combined gas chromatography-mass spectrometry (GC-MS) gave very similar ABA concentrations in the initial leaf samples. However, RIA analysis of crude aqueous extracts of pea seeds resulted in considerable overestimation of the amount of ABA present. Determinations of ABA content by GC-MS and RIA were similar after pea seed extracts had been purified by HPLC. Although the RIA could not be used to analyse ABA in crude extracts of pea seeds, it is likely that crude extracts of leaves of several other species may be assayed successfully.