Mr Lee was given seven days of medical leave after he had robot- assisted keyhole surgery yesterday to remove his cancerous prostate gland.
Defence Minister Ng Eng Hen, a former cancer surgeon, said on Facebook that he used to give patients four to six weeks of medical leave to recuperate.
"I would tell them that, it may be keyhole on the outside, but full surgery has been done inside.
Even after minimally invasive surgery, the body needs time to heal, (and) regain its energy and usual rhythm," he wrote.
Expressing hope that Mr Lee takes enough time to recover, Dr Ng said he is glad the surgery went well.
Robot-assisted keyhole surgery is a technique in which operations are performed through small incisions in the body, with the use of a robotic system.
Compared with open surgery, recovery is twice as quick.
Even so, urologists interviewed said that, like Dr Ng, they usually give patients four to six weeks of medical leave.
"Keyhole surgery operations are still major and complex," said Singapore Urological Association president Tan Yeh Hong.
After the prostate gland is removed, the bladder must be reconnected to the urethra.
Thus, complications such as infection, the risk of bleeding and incontinence could arise, he added.
The possibility of such complications is why Dr Michael Wong, consultant urologist at Mount Elizabeth Medical Centre, typically wards his patients for two weeks.
"We want to watch them like a hawk, because most of the complications happen in that timeframe," he said.
After that, patients should avoid strenuous activities "like golf or running a marathon" for another two to four weeks, depending on their age and pre- existing conditions, he added.
Emeritus Senior Minister Goh Chok Tong, who had prostate cancer surgery last November, offered this advice on Facebook: "Over the next few weeks, he must be careful not to inadvertently tear the surgical stitches, especially the internal wounds."
It was the reason he discouraged people from visiting when he was recuperating, "so as to rest as and when I wanted", wrote Mr Goh, who returned to work after a week, like Mr Lee is expected to.
Urologists said patients can sit up and walk immediately after surgery, but must take care not to strain themselves.
Said Dr Tan: "PM is quite a busy person.
I'm sure he will want to be there for the Budget.
Most people have no problem returning to office work after a week, if they must."
Deputy Prime Minister and Finance Minister Tharman Shanmugaratnam will deliver the Budget in Parliament on Monday.
Mr Lee's operation was done by Singapore General Hospital's lead urologist Christopher Cheng, a pioneer in using robots in surgery. Dr Wong said of Professor Cheng: "The PM is in good hands."
This article was first published on Feb 17, 2015.
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