This analysis shows that local hydration and anti-emetics policies for cisplatin treatment differed between participating centres in the De-ESCALaTE trial. The use of a triple anti-emetics regimen, 2.5 to 3 litres of IV fluids given before and during cisplatin chemotherapy as well as oral fluids advised post chemotherapy, were associated with a reduced incidence of SAEs with toxicities of interest (nausea, vomiting, dehydration and renal toxicities) of any grade. In addition, centres which had a policy to use diuretics had a lower incidence of severe (grade 3–5) acute toxicities of interest (nausea, vomiting, dehydration and renal toxicities).
The most widely accepted schedule of concomitant cisplatin with radiotherapy for locally advanced HNSCC has been 100mg/m2 given on a three-weekly basis, which was also the regimen used in the De-ESCALaTE trial (3). A phase III randomized non-inferiority trial of cisplatin 30mg/m2 once a week compared with cisplatin 100 mg/m2 once every 3 weeks in locally advanced HNSCC conducted in India, demonstrated that once-every-week cisplatin at 30mg/m2 was shown to have an inferior locoregional control albeit with less acute grade 3–5 toxicities than the three weekly cisplatin regimen (7). However, a subsequent phase II/III JCOG1008 trial comparing weekly cisplatin (40 mg/m2) with 3-weekly cisplatin (100 mg/m2) showed that weekly cisplatin was noninferior to 3-weekly cisplatin for overall survival and resulted in less frequent ≥ Grade 3 neutropenia, infection, renal and hearing impairment in high-risk HNSCC patients undergoing post-operative chemoradiotherapy (20). While some cancer centres have changed their concomitant cisplatin chemotherapy with radical and/or postoperative radiotherapy to a weekly regimen, the three-weekly cisplatin regimen at 100mg/m2 remains the standard of care at many centres.
A high dose of cisplatin (≥ 50 mg/m2) has a high emetic risk with 90% frequency of emesis and has the dose-limiting toxicity of nephrotoxicity (9). Therefore, its administration usually requires hydration and use of antiemetic agents, often necessitating inpatient overnight stay. However, studies have assessed the use of shorter durations of hydration with lower hydration volumes to facilitate outpatient ambulatory delivery of cisplatin (9). In addition, other strategies to minimize nephrotoxicity includes magnesium and diuretics such as mannitol in the hydration protocol. This is because magnesium depletion increases the severity of platinum-induced nephrotoxicity (10–12) and mannitol has been used to reduce the urine concentration of cisplatin to decrease its nephrotoxicity (13).
In a retrospective study, patients with lung cancer and other cancers were treated with cisplatin at a dose of ≥ 60 mg/m2 using a short hydration protocol consisting of a maximum of 2250 ml of hydration with mannitol and magnesium supplementation over a period of less than 5 hours on Day 1 or a conventional hydration protocol consisting of a maximum of 2600 ml of hydration over less than 8 hours on Day 1 with pre- and post-hydration for three days (14). It was shown that ≥ grade 1 elevated serum creatinine level was less frequent in the group receiving the short hydration protocol than in the group receiving conventional hydration (14). In two other prospective Japanese studies, the short hydration with cisplatin was shown to be safe without severe renal toxicities in regimens containing cisplatin (75 mg/m2) for patients with lung cancer (15–16). However, the safety of the short hydration policy with concurrent high-dose three weekly cisplatin and radiation in HNSCC has not been formally assessed.
This novel observational study using existing clinical trial data has strengths including detailed information on centre level policy for hydration and antiemetic use, high-quality data on relevant baseline and clinical characteristics for participants, and no loss to follow up. In addition, the use of bootstrapping increased the stability of the calibration and discrimination estimates for the prediction models (17). However, these results should be interpreted in light of certain limitations. Data on patient level hydration and anti-emetic use would have strengthened the conclusions, as use likely differs within centres depending on a patient’s clinical indication and a clinician’s preference. For example, for individuals using a PEG, a centre level policy advising patients to drink additional fluids orally after chemotherapy would not be relevant. This means that the ecological fallacy may be introduced if extrapolating these centre level findings to the individual (18). Additionally, stepwise regression models can produce biased regression coefficients, CIs and p values (19). Therefore, multivariable regression models were produced for the two outcomes with all centre level predictor variables, with and without all baseline variables (Supplementary Tables 9–12). In the presence of baseline characteristics, use of oral fluids, IV fluids given pre and during chemo, and use of diuretics were weakly associated with severe acute toxicities of interest (grade 3–5), but the use of a triple anti-emetics regimen pre and post chemotherapy, increased volumes of IV fluids given before and during cisplatin chemotherapy as well as oral fluids advised post chemotherapy were still associated with SAEs with toxicities of interest of any grade.
We recommend the use of a triple anti-emetic regimen, adequate hydration of 2.5-3 litres before and during chemotherapy as well as advising patients to take oral fluids and diuretics when giving concomitant cisplatin (100mg/m2 three-weekly) with radiotherapy for locally advanced HPV + head and neck cancers. These measures may reduce SAEs including hospitalization, life-threatening complication, death, significant disability/incapacity or permanent impairment/damage related to nausea, vomiting, dehydration and/or acute renal injury.