Berenberg upgraded AstraZeneca to 'buy' from 'hold' and raised the price target to 5,200p from 4,800p, saying that Oncology will drive future growth.Berenberg noted that AZN shares reached highs of 4,800p during last year's Pfizer approach. Since then, sentiment has weakened and the shares are not far off 12-month lows."Nevertheless, we think the oncology pipeline remains robust, and will underpin a return to double-digit growth beyond 2017, and this is not adequately reflected in the valuation today," said the bank.It said the company has made good progress in its oncology pipeline. Lynparza is approved in the US and Europe, and should be a blockbuster drug, said the bank, which expects the oncology franchise to grow from a low of $2.8bn this year to $6.9bn by 2013.In terms of important oncology catalysts in the next 12 months, it said pivotal data for AZD9291 are expected soon and the drug could be approved by year end.At 0909 BST, the company's shares were up 0.7% at 4,151p.