* Sees low single-digit percentage 2018 drug sales growth
* 2018 core EPS guidance $3.30-3.50 vs consensus $3.61
* CEO says drugmaker "steadily turning a corner"
* Tech deals with Alibaba, Tencent as China sales shine (Adds further CEO quotes, China deals, analyst comments)
LONDON, Feb 2 (Reuters) - AstraZeneca expects a return to drug sales growth in 2018 as new medicines win market share and the group puts patent losses behind it, although the need to invest in launches will weigh on profits.
AstraZeneca has suffered the industry's biggest patent cliff since 2012, which wiped out more than half of its sales, but Chief Executive Pascal Soriot said it was "steadily turning a corner".
After a 5 percent fall in 2017, the group expects drug sales this year to grow at a low single-figure percentage rate, driven by new treatments for cancer in particular.
"We have a pipeline that is over-sized relative to the current size of our company," Soriot said.
"That's a good thing because over the next two or three years we are going to be able to drive a very strong growth rate - but of course it creates a need to resource those launches."
The need to invest heavily in promoting new medicines will hold back profits this year, with the company predicting core earnings per share (EPS) of $3.30 to $3.50 - below the Thomson Reuters consensus of $3.61.
The weak profit guidance pushed the shares lower despite better-than-expected fourth-quarter profits. At 1240 GMT the stock was 0.8 percent lower.
"While the EPS guidance range suggests modest downside to consensus, this clearly reflects plans to invest more aggressively behind new launches, which investors should be comfortable with," said Deutsche Bank analyst Richard Parkes.
Revenue last year was boosted by a bumper haul of "externalisation" deals, involving asset sales and collaborations with other companies, which some analysts have criticised for flattering results.
Such deals contributed $2.3 billion in 2017 out of total revenue of $22.5 billion, but AstraZeneca said they had peaked and would decline in 2018.
AstraZeneca has had some notable new product successes recently, with oncology pills Tagrisso and Lynparza both doing well and progress in other areas, including novel treatments for lung disorders.
Its heart drug Brilinta and Farxiga for diabetes have also both just breached the $1 billion annual sales mark, while its business in China is outgrowing rivals and Soriot said he expected continued growth above 20 percent.
AstraZeneca also announced two new deals with Chinese tech giants Alibaba and Tencent on Friday, designed to optimise drug use and fight counterfeit medicines.
Still, the pace of its turnaround remains uncertain pending further clinical trial read-outs in the multibillion-dollar cancer immunotherapy market, where AstraZeneca's Imfinzi is going head to head with rival drugs from Merck & Co, Bristol-Myers Squibb and Roche.
"The very successful launch in the coming months of Imfinzi in lung cancer is crucial if AstraZeneca is going to make up lost ground," said Trinity Delta analyst Mick Cooper.
AstraZeneca suffered the biggest ever daily fall in its shares last July, following disappointing initial results from a lung cancer trial dubbed Mystic. Since then the shares have rallied, helped by good news from two other studies.
Further data from the Mystic trial is due in the first half of this year.
Fourth-quarter core EPS, which excludes some items, increased 7 percent to $1.30 cents on revenue of $5.78 billion, helped by one-off tax gains. Analysts, on average, had forecast earnings of 84 cents on revenue of $5.46 billion. (Reporting by Ben Hirschler; editing by Keith Weir and Elaine Hardcastle)