Charleston, S.C. ? Jon Lester passed a major test Thursday. The Red Sox pitcher has a much bigger one ahead later this month.

Lester made his first start of the year Thursday night for the Class-A Greenville Drive as he attempts to return to Boston’s rotation after an offseason of cancer treatments and uncertainty. He shut out the New York Yankees’ affiliate, the Charleston RiverDogs, on one hit over four innings before coming out.

The 23-year-old pitcher is due for the next of his three-month checkups later in April to see if he’s still cancer free. He had put all his concentration into his comeback during spring training. But the looming test has been on his mind recently.

Lester was diagnosed with anaplastic large cell lymphoma late last season.

He had established himself as a rookie a year ago, going 7-2 with a 4.76 earned-run average.