diff --git a/protobuf/grpc_service.proto b/protobuf/grpc_service.proto
index b8d6674..451dd74 100644
--- a/protobuf/grpc_service.proto
+++ b/protobuf/grpc_service.proto
@@ -1050,6 +1050,13 @@ message InferResponseStatistics
   //@@     The count and cumulative duration for empty responses.
   //@@
   StatisticDuration empty_response = 5;
+
+  //@@  .. cpp:var:: StatisticDuration cancel
+  //@@
+  //@@     The count and cumulative duration, for cleaning up resources held by
+  //@@     a cancelled request, for cancelled responses.
+  //@@
+  StatisticDuration cancel = 6;
 }
 
 //@@