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Parotid gland shrinkage during IMRT predicts the time to Xerostomia resolution.

Sanguineti G, Ricchetti F, Wu B, McNutt T, Fiorino C - Radiat Oncol (2015)

Bottom Line: For each parotid gland, the percent change relative to the planning volume was calculated and combined as weighted average.Patients were pooled in 4 groups based on median values of both mid-treatment shrink (cut-off: 19.6%) and mean WA parotid pl-D (cut-off: 35.7 Gy).Patients with a higher than median parotid dose at planning and who showed poor shrinkage at mid treatment are the ones with the outcome significantly worse (3-yr rate of xerostomia ≈ 50%) than the other three subgroups (3-yr rate of xerostomia ≈ 10%).

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Johns Hopkins University, Baltimore, MD, USA. gsangui1@gmail.com.

ABSTRACT

Purpose: To assess the impact of mid-treatment parotid gland shrinkage on long term xerostomia during IMRT for oropharyngeal SCC.

Methods and materials: All patients treated with IMRT at a single Institution from November 2007 to June 2010 and undergoing weekly CT scans were selected. Parotid glands were contoured retrospectively on the mid treatment CT scan. For each parotid gland, the percent change relative to the planning volume was calculated and combined as weighted average. Patients were considered to be xerostomic if developed GR2+ dry mouth according to CTCAE v3.0. Predictors of the time to xerostomia resolution or downgrade to 1 were investigated at both uni- and multivariate analysis.

Results: 85 patients were selected. With a median follow up of 35.8 months (range: 2.4-62.6 months), the actuarial rate of xerostomia is 26.2% (SD: 5.3%) and 15.9% (SD: 5.3%) at 2 and 3 yrs, respectively. At multivariate analysis, mid-treatment shrink along with weighted average mean parotid dose at planning and body mass index are independent predictors of the time to xerostomia resolution. Patients were pooled in 4 groups based on median values of both mid-treatment shrink (cut-off: 19.6%) and mean WA parotid pl-D (cut-off: 35.7 Gy). Patients with a higher than median parotid dose at planning and who showed poor shrinkage at mid treatment are the ones with the outcome significantly worse (3-yr rate of xerostomia ≈ 50%) than the other three subgroups (3-yr rate of xerostomia ≈ 10%).

Conclusion: For a given planned dose, patients whose parotids significantly shrink during IMRT are less likely to be long-term supplemental fluids dependent.

No MeSH data available.


Related in: MedlinePlus

Actuarial rate of physician-reported GR2+ xerostomia by both mid-treatment combined parotid gland shrinkage and mean weighted average parotid dose at planning. Low/high represent values below/above median values of 19.6% and 35.7Gy for mid-treatment shrinkage and mean combo parotid dose, respectively.
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Fig2: Actuarial rate of physician-reported GR2+ xerostomia by both mid-treatment combined parotid gland shrinkage and mean weighted average parotid dose at planning. Low/high represent values below/above median values of 19.6% and 35.7Gy for mid-treatment shrinkage and mean combo parotid dose, respectively.

Mentions: Patients were pooled in 4 groups based on median values of both mid-treatment shrink (cut-off: 19.6%) and mean WA parotid pl-D (cut-off: 35.7 Gy). Figure 2 illustrates the time to xerostomia resolution/downgrade to GR1 by each group, disregarding BMI. Patients with a higher than median parotid dose at planning and who showed poor shrinkage at mid treatment are the ones with the worst outcome (3-yr rate of GR2+ xerostomia ≈ 50%); conversely, despite a higher than median parotid dose at planning, patients with an average mid treatment shrink larger than 19.6% had a time to xerostomia resolution/downgrade similar to that of patients planned to receive a lower mean dose to the parotids (for both subgroups, 3-yr rate of GR2+ xerostomia <10%). The difference between patients with high pl-D/low shrink and each of the other 3 groups is statistically significant (p < 0.05).Figure 2


Parotid gland shrinkage during IMRT predicts the time to Xerostomia resolution.

Sanguineti G, Ricchetti F, Wu B, McNutt T, Fiorino C - Radiat Oncol (2015)

Actuarial rate of physician-reported GR2+ xerostomia by both mid-treatment combined parotid gland shrinkage and mean weighted average parotid dose at planning. Low/high represent values below/above median values of 19.6% and 35.7Gy for mid-treatment shrinkage and mean combo parotid dose, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4307228&req=5

Fig2: Actuarial rate of physician-reported GR2+ xerostomia by both mid-treatment combined parotid gland shrinkage and mean weighted average parotid dose at planning. Low/high represent values below/above median values of 19.6% and 35.7Gy for mid-treatment shrinkage and mean combo parotid dose, respectively.
Mentions: Patients were pooled in 4 groups based on median values of both mid-treatment shrink (cut-off: 19.6%) and mean WA parotid pl-D (cut-off: 35.7 Gy). Figure 2 illustrates the time to xerostomia resolution/downgrade to GR1 by each group, disregarding BMI. Patients with a higher than median parotid dose at planning and who showed poor shrinkage at mid treatment are the ones with the worst outcome (3-yr rate of GR2+ xerostomia ≈ 50%); conversely, despite a higher than median parotid dose at planning, patients with an average mid treatment shrink larger than 19.6% had a time to xerostomia resolution/downgrade similar to that of patients planned to receive a lower mean dose to the parotids (for both subgroups, 3-yr rate of GR2+ xerostomia <10%). The difference between patients with high pl-D/low shrink and each of the other 3 groups is statistically significant (p < 0.05).Figure 2

Bottom Line: For each parotid gland, the percent change relative to the planning volume was calculated and combined as weighted average.Patients were pooled in 4 groups based on median values of both mid-treatment shrink (cut-off: 19.6%) and mean WA parotid pl-D (cut-off: 35.7 Gy).Patients with a higher than median parotid dose at planning and who showed poor shrinkage at mid treatment are the ones with the outcome significantly worse (3-yr rate of xerostomia ≈ 50%) than the other three subgroups (3-yr rate of xerostomia ≈ 10%).

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Johns Hopkins University, Baltimore, MD, USA. gsangui1@gmail.com.

ABSTRACT

Purpose: To assess the impact of mid-treatment parotid gland shrinkage on long term xerostomia during IMRT for oropharyngeal SCC.

Methods and materials: All patients treated with IMRT at a single Institution from November 2007 to June 2010 and undergoing weekly CT scans were selected. Parotid glands were contoured retrospectively on the mid treatment CT scan. For each parotid gland, the percent change relative to the planning volume was calculated and combined as weighted average. Patients were considered to be xerostomic if developed GR2+ dry mouth according to CTCAE v3.0. Predictors of the time to xerostomia resolution or downgrade to 1 were investigated at both uni- and multivariate analysis.

Results: 85 patients were selected. With a median follow up of 35.8 months (range: 2.4-62.6 months), the actuarial rate of xerostomia is 26.2% (SD: 5.3%) and 15.9% (SD: 5.3%) at 2 and 3 yrs, respectively. At multivariate analysis, mid-treatment shrink along with weighted average mean parotid dose at planning and body mass index are independent predictors of the time to xerostomia resolution. Patients were pooled in 4 groups based on median values of both mid-treatment shrink (cut-off: 19.6%) and mean WA parotid pl-D (cut-off: 35.7 Gy). Patients with a higher than median parotid dose at planning and who showed poor shrinkage at mid treatment are the ones with the outcome significantly worse (3-yr rate of xerostomia ≈ 50%) than the other three subgroups (3-yr rate of xerostomia ≈ 10%).

Conclusion: For a given planned dose, patients whose parotids significantly shrink during IMRT are less likely to be long-term supplemental fluids dependent.

No MeSH data available.


Related in: MedlinePlus