34 QoL Chewing scores (mean ±SD) clustered by time (baseline, ≤1 year, ±1 year, 2-4 years, 8-10 years). In case SE instead of SD was provided, SD scores were calculated as , where N = the number of participants Subgroups of studies: 2=Bekiroglu et al. (2011) (I:no RT, II:RT); 3=Devine et al. (2001) (I:LSM, II:V/MLR); 5=Fang et al. (2014) (I:FF rec., II:no FF rec.); 6=Ghai et al. (2021) (I:T1 without RT, II:T2 without RT, III:T1 and T2 with RT); 7=Gu et al. (2021) (I:ND with submandibular gland preservation, II:conventional ND); 9=Larson et al. (202) (I:lateral FOM, II:anterior FOM, III:alveolar ridge with FOM); 11=W. Li et al. (2016) (I:PMMF, II:RFFF); 12=X. Li et al. (2016) (I:RT pre-Tx, II:RT post-Tx, III:RT pre- and post-Tx, IV:no RT); 14=Rogers et al. (2004) (I:nil, II:rim res., III:segment res.); 16=Sakthivel et al. (2017) (I:surgery, II:adjuvant therapy); 17=Seferin et al. (2020) (I:sentinel lymph node biopsy, II:cervical ND level I-III); 21=Wu et al. (2020) (I:classic ALTFF, II:chimeric ALTFF); 22=Yan et al. (2017) (I:long-term survivors, II:non-survivors); 24=Yuan et al. (2016) (I:RFFF, II:ALTFF); 25=Yue et al. (2018) (I:tongue, II:other, III:no rec., IV:rec.); 26=Zhang et al. (2013) (I:≤ 40 years, II:≥ 40 years). ALTFF=anterolateral thigh perforator free flap, FF=free flap, FOM=Floor of mouth, LSM=lip-split mandibulotomy, ND=neck dissection, nil=no resection, PMMF=pectoralis major myocutaneous flap, rec= reconstruction, RFFF=radial forearm free flap, res=resection, RT=radiotherapy, SD=standard deviation, SE=Standard Error, Tx=Treatment, V/MLR=visor or mandibular lingual release Figure 2. QoL chewing scores clustered by time