Nginx proxy_cache_purge alternative - get file out of cache

I seems that the proxy_cache_purge directive is supported only in the commercial nginx version.

Is there an alternative way I could get a file/path/key out of the cache?

Below my sample proxy_pass configuration with enabled caching:

...

# Configure proxy cache
proxy_cache_path    /data/nginx/cache levels=1:2 keys_zone=demo:10m;

proxy_pass          http://127.0.0.1:90$uri;

proxy_set_header    Host $host;
proxy_set_header    X-Real-IP $remote_addr;
proxy_set_header    X-Forwarded-For $proxy_add_x_forwarded_for;

proxy_cache         demo;
# proxy_cache off;

proxy_cache_key     $host$uri$is_args$args;
proxy_cache_valid   any 1m;

...