* Wall Street up in afternoon trading
* Samsung helps lift Asian shares to 7-week highs
* Dollar gains vs euro and Swiss franc
* Bank of Japan holds off on fresh stimulus (Updates to U.S. afternoon trading)
By Caroline Valetkevitch
NEW YORK, Oct 7 (Reuters) - World stock indexes edged higher on Wednesday with a rebound in biotech shares boosting U.S. equities and as oil prices resumed an upward move in volatile trading.
U.S. stocks rose modestly, but concern about corporate earnings just ahead of the third-quarter reporting season kept a lid on optimism. Reduced profit forecasts from Adobe ADBE.O and Yum Brands YUM.N added to gloom about the earnings picture.
Oil prices struggled to extend their recent rally as U.S. government data showed domestic crude inventories rose 3.1 million barrels last week, more than forecast.
The U.S. dollar rose against the euro and the Swiss franc, while the yen gained against the dollar after the Bank of Japan left monetary policy unchanged. ID:nL1N12713A The dollar index .DXY was up 0.1 percent.
Although the Bank of Japan held off on expanding stimulus on Wednesday, expectations of more support rather than less are growing as worries mount over a global economic slowdown. This week, the International Monetary Fund again cut its growth forecast.
The potential for more stimulus from the European Central Bank and Bank of Japan has contributed to a backdrop of accommodative central bank policy, along with expectations that a Federal Reserve rate increase will remain on hold until 2016.
On Wall Street, the S&P 500 health care index .SPXHC was up 1.3 percent, in the biggest boost to the S&P 500, while the Nasdaq Biotech index .NBI was up 1.9 percent, after recent steep losses.
The Dow Jones industrial average .DJI rose 69.95 points, or 0.42 percent, to 16,860.14, the S&P 500 .SPX gained 10.06 points, or 0.51 percent, to 1,989.98 and the Nasdaq Composite .IXIC added 25.29 points, or 0.53 percent, to 4,773.65.
Shares of Adobe were down 6 percent at $80.05.
"Tech investors are very worried heading into earnings season and this has been an overhang with many of the tech stalwarts having a bullseye on their back," said Daniel Ives, senior analyst at FBR Capital.
Analysts have been cutting forecasts for U.S. third-quarter earnings since the start of the quarter.
But even as Citi strategists have warned that analyst earnings forecasts are too optimistic, they have backed the view that the bull market has yet to die, predicting global equities will rise 20 percent through to the end of 2016. The market is "already pricing in" a gloomier scenario, they argue.
The pan-European FTSEurofirst 300 .FTEU3 closed up 0.1 percent, while MSCI's all-country world stock index .MIWD00000PUS was up 0.8 percent.
Asian shares reached a seven-week high. South Korea's Samsung Electronics (KS:005930) 005930.SS helped sentiment when it reported an estimated quarterly profit that exceeded analyst expectations.
Brent LCOc1, the global crude benchmark, was up 25 cents at $52.17 a barrel by 12:22 p.m. (1622 GMT). At its session high, Brent was up more than $1. It turned negative before then edging higher.
The West Texas Intermediate (WTI) benchmark for U.S. crude CLc1 was down 5 cents to $48.48 a barrel. It had also been up more than $1 at its session high.
U.S. Treasuries prices fell. Benchmark 10-year Treasuries US10YT=RR were down 10/32 in price to yield 2.072 percent, up almost 4 basis points from late Tuesday.