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Table 2 Parotid volumetric and dosimetric changes in HNSCC or NPC during curative RT or CRT

From: Adaptive radiotherapy for head and neck cancer

StudySample Size (n)Re-Scan TimingMean Parotid Volume Reduction (Range) by Fraction (Fx) 10Mean Parotid Volume Reduction (Range) by Fx 20Mean Parotid Volume Reduction (Range) by End of TreatmentDosimetric: Mean Parotid Dose Change (Range)
Bhide IJROBP 2010 [8]20 (10 OPC, 6 Laryng or Hypoph, 4 NPC)Weeks 2, 3, 4, 514.7% NS35% NSWithout ART: 2.8 Gy increase ipsi
Capelle Clin Oncol 2012 [10]20 (17 HNSCC, 3 NPC)Fx 1517.5% NS (−1 to 46%)With ART: 0.6 Gy reduction NS
Lu Chin Med J 2012 [14]43 (43 NPC)Fx 2035.5 to 36.8% *
Beltran J Appl Clin Med 2012 [18]16 (7 OPC, 5 OC, 1 Hypoph, 1 NPC, 2 NS)Fx 15, 2522% NS30% NSWithout ART: 4.7% increase Ipsi 6.1% increase Contra
Schwartz Radiother Oncol 2013 [21]22 (22 OPC)Daily scans, Weekly recalc15% NS (−19 to 25%)26% NS (−8 to 48%)1 ART re-plan: 1.3 Gy reduction ipsi 2 ART re-plans: 4.1 Gy reduction ipsi
Chitapanarux J Radiat Res 2015 [11]17 (17 NPC)Fx 1730.5% ipsi 24.3% contraWith ART: 1.1 Gy reduction Contra Ipsilateral not significant (0.9 Gy)
Huang Radiat Oncol 2015 [24]19 (19 NPC)Every 5 Fx14.4 to 15.8% *38.0 to 39.2% *Without ART: 3.09 Gy to 5.6 Gy increase *
Dewan Asian Pac J 2016 [12]30 (15 OPC, 10 OC, 5 Hypoph)Fx 2033.65% ipsi 31.06% contraWith ART: 5.6 Gy reduction ipsi Contralateral not significant (2.7 Gy)
Zhang J Med Radiat Sci 2017 [34]39 (39 NPC)Fx 10, 20, 3015.27% ipsi37.49% ipsi 34.55% contra
Mahmoud Technol Cancer Res Treat 2017 [15]22 (11 OPC, 7 OC, 2 Laryng, 1 Hypoph, 1 NPC)Fx 15, 2718.2 to 19.0% * for definitive (3 to 32%) 10.0 to 16.6% * for adjuvant (5 to 44%)30.1 to 30.9% * for definitive (11 to 52%) 23.1 to 25.3% * for adjuvant (3 to 41%)Without ART:
15.4 to 16.4% increase * for definitive (−30 to 76%) 9.1 to 10.4% increase * for postop (−25 to 70%) Neither significant given large heterogeneity
Loo Clin Oncol 2011 [17]5 (3 OPC, 1 OC, 1 Laryng)Weekly30.2% Ipsi (17.1 to 55.8%) 17.5% Contra (15.6 to 48.5%)Without ART: 7.6 Gy increase Ipsi (2.5 to 19 Gy) 7.3 Gy increase Contra (1.1 to 11.6 Gy)
Fung Med Dosim 2012 [19]10 (10 NPC)Fx 21, 31 approx.32.44 to 33.31% *With ART: 0.75 Gy reduction (right, p = 0.046) 1.25 Gy reduction (left, p = 0.053)
Fung J Radiat Res 2014 [23]30 (30 NPC)Every 2 Fx47.54% NS
Hunter IJROBP 2013 [35]18 (18 OPC)Weekly13.31% NSWithout ART: 0.92 Gy (median) increase NS (−4.9 to 8.4 Gy; not sig) 23/36 parotids had an increase (2.2 Gy median)
Jin Radiat Oncol 2013 [5]9 (9 NPC)Fx 2338.4 to 40.68% *
Castelli Radiat Oncol 2015 [3]15 (11 OPC, 2 OC, 1 Laryng, 1 Hypoph)Weekly28.3% NSWithout ART: 67% of pts.: 4.8 Gy increase NS 33% of pts.: 3.9 Gy decrease NS With ART: Of those with overdosed parotids: 5.1Gy decrease NS (0.6 to 12.2 Gy)
Yao Biomed Res Int 2015 [36]50 (50 NPC)Every 5 Fx35% NS (6.8 to 69.4%)Without ART: 3.52 Gy (11.38%) increase NS (−1.51 to 30.57%) Weight loss correlated with mean parotid dose
Zhang Radiother Oncol 2016 [26]13 (13 OPC)Weekly34.51% ipsi (10 to 57.6%) 27.98% contra (−5.2 to 57.3%)Without ART: 16/23 parotids overdosed: 4.1 Gy increase NS (0.5 to 11.5 Gy) 3 ART re-plans: 3.1 Gy reduction NS 6 ART re-plans: 3.3 Gy reduction NS
Hu BMC Cancer 2018 [40]40 (40 NPC)Median Fx 2217.2% Ipsi 20% ContraWith ART: 0.7 Gy reduction Ipsi Contralateral not significant (0.1 Gy)
Lee IJROBP 2008 [4]10 (2 OPC, 5 NPC, 1 SN, 1 OPC + NPC, 1 UP)Daily MV-CTWithout ART: 3 Gy (11%) NS (−6 to 42%) Parotid glands migrating closer to target volume had higher changes in mean dose
Fiorentino Br J Radiol 2012 [41]10 (4 OPC, 5 OC, 1 Hypoph)Daily43.5% Ipsi 44.0% Contra
Range of median parotid volume reductions reported in the included studies15%10 to 37%13 to 48%
  1. All studies reported an average decrease in parotid volume at time of re-scan; however, there was wide heterogeneity between and even within studies, with a few patients actually having an increase in parotid gland volume by end of treatment. This was associated with variable reductions in mean parotid dose by adaptive re-planning and suggests that ART may not be appropriate for all patients. However, ART does appear to reduce mean parotid dose in patients whose parotids experience an unintended overdosage secondary to anatomic changes throughout treatment, which has been associated with reduced predicted xerostomia. However, clinical correlation is still lacking between ART and prospective toxicity data. Note that a negative volumetric change reported above means that this structure increased in size (e.g. -1% indicates a 1% increase in volume). A negative dosimetric change means that it decreased in the dose received (e.g. -10% indicates a 10% decrease in mean parotid dose)
  2. “- “information was either not available or was not directly comparable to other volumetric/dosimetric data reported and thus not included
  3. NS” parotid side was not specified
  4. “* “parotid side (left or right) was specified; however, ipsilateral and contralateral designation were not specified
  5. Ipsi “ipsilateral parotid
  6. Contra “contralateral parotid
  7. HNSCC Head and Neck Squamous Cell Carcinoma, OPC Oropharyngeal Cancer, OC Oral Cavity Cancer, NPC Nasopharyngeal Cancer, Laryng Laryngeal Cancer, Hypoph Hyopharyngeal Cancer, NS Head and Neck Squamous Cell Carcinoma, Site Not Specified, SN Sinonasal Cancer, UP Head and Neck Squamous Cell Carcinoma of Unknown Primary