* 2012 sales up 7 pct, core earnings up 11 pct
* To pay 7.35 Sfr per share dividend for 2012
* Some investors had speculated about special dividend
* Shares fall 1.3 percent, underperform sector
By Caroline Copley
BASEL, Jan 30 (Reuters) - Swiss drugmaker Roche forecast a rise in sales and profits this year, helped by new cancer medicines it hopes will shield it from the patent expiries ravaging many rivals.
Roche, the world's largest maker of cancer drugs, said on Wednesday it hoped sales would grow in line with 2012, when they rose 7 percent to 45.5 billion Swiss francs ($49 billion).
The Basel-based group also said it was aiming for core earnings, up 11 percent in 2012, to increase ahead of sales.
That assessment was more upbeat than cross-town rival Novartis, which last week guided for a fall in profit in 2013 as it grapples with competition from cheaper copies of its top-selling product.
Roche has been spared the pain from a wave of patent expiries hitting many rivals, as most of its medicines do not face imminent generic competition.
It also has high hopes for new treatments like skin cancer drug Zelboraf and breast cancer medicine Perjeta, and some analysts predicted its guidance for 2013 would prove cautious.
"In our opinion, sales in 2013 should pick up more strongly; we see the guidance as conservative as usual," said ZKB analyst Michael Nawrath.
Roche proposed a dividend of 7.35 francs per share, compared with 6.80 francs a year ago, and pledged to keep hiking shareholder payouts.
This wasn't enough for some investors, though, who had speculated the group might pay a special dividend.
Roche Chief Executive Severin Schwan dismissed this, pointing out the group's net debt to assets ratio of 16 percent was still above its 0-15 percent target range.
At 0900 GMT, shares in Roche, which have gained 9.5 percent so far this year, were down 1.3 percent at 198.8 francs compared with a 0.1 percent weaker European healthcare index.
The group said 2012 core earnings per share reached 13.62 francs, in line with analyst forecasts, helped by cost cutting and sales of its three biggest-selling cancer medicines - Rituxan, Herceptin and Avastin.
Some analysts have raised concerns about the loss of market exclusivity on chemotherapy drug Xeloda at the end of 2013 and possible competition for hepatitis C drug Pegasys from other oral treatments, which they say could drag on Roche's medium-term growth.
However, the group is developing follow-on medicines to try and fend off anticipated competition from so-called biosimilar copies of its cancer drugs.
Sales of Perjeta, a treatment for women with a particularly aggressive form of breast cancer, were 56 million francs so far, up from 26 million in the third quarter.
Perjeta is a follow-on to Roche's current second-biggest seller Herceptin and part of its strategy to develop new drugs to extend the longevity of its best-selling brands. It won approval from U.S. regulators in June.
U.S. regulators are expected to decide on Feb. 26 whether to approve another new breast cancer drug called T-DM1, which Roche hopes will be used in combination with Perjeta, giving further protection against the biosimilar threat.
"We do not only believe that we will defend the franchise, we believe that with those two important new medicines we will actually grow the franchise in the medium to long term," Schwan told journalists in Basel.
Roche is hoping to duplicate this defence strategy with GA101 - a treatment for chronic lymphocytic leukaemia which it bills as a better product than its original Rituxan.
Key data due later this year will provide clues as to whether Roche will be able to convince doctors to move patients to GA101 from Rituxan, which had sales of 6.7 billion francs in 2012 but loses patent protection in Europe at the end of 2013.