* FTSE 100 rise 0.5 pct
* Insurers rally after Hurricane Irma downgraded
* AstraZeneca jumps after positive results for cancer drugs (Adds closing prices)
LONDON, Sept 11 (Reuters) - Britain's top share index closed higher on Monday, boosted by financial stocks which surfed an insurance rally across Europe and the United States as estimates of the cost of Hurricane Irma dropped.
The blue chip FTSE 100 index was up 0.6 percent at 7,413.59 points, while mid caps gained 0.4 percent.
The FTSE 350 non-life insurance index jumped 2.1 percent, leaving it on track for its biggest one-day gain since April, with shares in Lancashire Holdings, Beazley , Esure and Hiscox all rising between 2.9 percent to 10.3 percent.
Provident was the top gainer with a 3.8 percent rise as other British financial shares rose in line with Europe and Wall Street after Hurricane Irma weakened to a Category 1 storm.
"Insured losses (overall) are now expected to be less than many feared," Credit Suisse analysts said after the estimated insured loss in the United States resulting from Irma was cut to $20-40 billion.
In other sectors, AstraZeneca's shares were among the biggest gainers on the FTSE, rising 2.1 percent after reassuring results from two of its lung cancer drugs.
The pharma firm's shares are yet to recover from a 15 percent plunge in July, when initial results from its advanced lung cancer study, known as Mystic, failed.
"(AstraZeneca) now has a good chance of growing the opportunity from what was previously expected in Stage III lung cancer," analysts at Liberum said in a note.
"If the reaction moves much beyond this, the shares would be starting once again to price a chance of success for Mystic," they added.
Among fallers, precious metals miners Fresnillo and Randgold Resources were on the back foot as the price of safe-haven gold fell, while shares in Primark-owner Associated British Foods were the biggest FTSE decliners, down 5 percent after giving a full-year trading update.
(Reporting by Kit Rees and Julien Ponthus; Editing by Toby Chopra)