Fig. 3

Correlation between the accumulative dose of S-1 and a change in the tear volume. Based on the tear volume at the start of the oral administration of S-1, change in the tear volume was estimated. Tear volume was generally monitored every two weeks during the course of the treatment. Occasionally, data taken two days after the end of a course were included. a “Watering eyes” group (y = 0.00072× + 5.46; rs = 0.463; r² = 0.264; P < 0.01, Spearman’s correlation). b “no watering eyes” group (y = − 0.00004× – 4.60; rs = 0.197; r² = 0.00045)