Corrupted SSTables

After 3 month of working, we noticed that number of compaction tasks were growing (~600 pending tasks). SStables verification shows that some of them were corrupted. Repairing didn't help (it was crashing with error).
Also some of requests (f.e. select * from fetcher where domain=8289511971670945261 and uri=-5417197141545933706; ) fails with next error:

Traceback (most recent call last):
File "/var/cassandra/apache-cassandra-3.9/bin/cqlsh.py", line 1264, in perform_simple_statement
result = future.result()
File "/var/cassandra/apache-cassandra-3.9/bin/../lib/cassandra-driver-internal-only-3.5.0.post0-d8d0456.zip/cassandra-driver-3.5.0.post0-d8d0456/cassandra/cluster.py", line 3650, in result
raise self._final_exception
error: unpack requires a string argument of length 4

Table chema:

CREATE TABLE fetcher (
domain bigint,
uri bigint,
date date,
content_length int,
elapsed float,
encoding text,
fetched_time bigint,
flinks frozen<set<tuple<bigint, bigint»>,
flinks_count int,
html_fingerprint bigint,
indexed boolean,
adult boolean,
kws_count int,
lang_id int,
last_updated bigint,
redirect_url tuple<bigint, bigint>,
revisit_date date,
revisit_interval int,
status_code int,
tokens_fingerprint bigint,
uris frozen<set<bigint»,
url text,
PRIMARY KEY (domain, uri, date)
) WITH CLUSTERING ORDER BY (uri ASC, date DESC)
AND bloom_filter_fp_chance = 0.1
AND caching = {'keys': 'ALL', 'rows_per_partition': 'NONE'}
AND comment = 'fetcher history'
AND compaction = {'class': 'org.apache.cassandra.db.compaction.LeveledCompactionStrategy',
'sstable_size_in_mb': '256',
'tombstone_threshold': '.2'}
AND compression = {'chunk_length_in_kb': '64',
'class': 'org.apache.cassandra.io.compress.LZ4Compressor'}
AND crc_check_chance = 1.0
AND dclocal_read_repair_chance = 0.1
AND default_time_to_live = 0
AND gc_grace_seconds = 864000
AND max_index_interval = 2048
AND memtable_flush_period_in_ms = 0
AND min_index_interval = 128
AND read_repair_chance = 0.5
AND speculative_retry = '99PERCENTILE';

Corrupted SSTable.