A Long Island mom says her teenage son, in remission from a rare form of leukemia, has been ripped from her arms and ordered back into a cancer ward after his doctors called Child Protective Services over her ending his chemotherapy.

“Obviously I do not want to do chemo,” Nick Gundersen, 13, told The Post over the phone from his bed in NYU Winthrop Hospital in Mineola, where he’s been fitted with a tracking device on his wrist, with his room watched by security guards at all times. “It makes me feel sick.”

Gundersen was fresh out of school and looking forward to summer vacation when he was diagnosed with acute myeloid leukemia in June, according to his mom, Candace.

After nearly a month in Cohen’s Children Hospital, the karate black-belt and Boy Scout was sleeping 18 hour days and had lost 25 percent of his weight, as both the cancer and chemo rocked his body.

He was eventually allowed to transition to outpatient treatment, but during a check-up in late August doctors said they wanted to readmit him.

The only problem was that his mom had since learned that doctors at the hospital had misdiagnosed Nick’s malady — he actually had mixed phenotype acute leukemia, a much rarer form of the cancer, she said.

Candace, eager to get a second opinion and treatment at another hospital, refused to readmit Nick and brought him home in early September.

Cohen Children’s then called Child Protective Services on the family, she said.

Police and CPS carried Nick from his home at 3 a.m., loaded him into the back of an ambulance, and rushed him back to the hospital, according to Candace.

On Sept. 11, Nick was transferred to NYU Winthrop, where his chemo was reinstated. By ­October he had beaten the cancer into remission.

Candace was overjoyed by her son’s against-the-odds progress, even as the doctors warned her that Nick would need to continue chemotherapy for some time to ensure the cancer didn’t return.

She balked, opting to again pull her son from the hospital and head to Florida to seek “preventative nontoxic therapy,” Candace said.

They hadn’t been in the Sunshine State long when Candace was contacted by CPS, ordering her to return her son for chemotherapy or face arrest.

Candace begrudgingly complied, but she’s fighting CPS’ court order keeping her frail son in a cancer ward.

“They’re pumping this biohazard into my son’s body. I feel like I’m in a Frankenstein movie,” said the mom. “I should have the right to decide what’s in the best interest of my son now that he is in remission.”

Nick, who bemoaned the fact that he isn’t even allowed to have his friends visit, agreed.

”If I truly believed I needed chemo, I would call 911,” the teen insisted. “But I do not think that.”

A spokesperson for NYU Winthrop, where about a dozen protesters rallied on Nick’s behalf Friday, insisted in a statement that Nick is receiving treatment that is up to “the highest standards of medical care and is a ­result of collaboration with the child’s legal guardian.”

A spokesman for the Suffolk County Department of Social Services, which oversees the local CPS, declined to comment extensively about the case, saying only that they were “proceeding in accordance with the Suffolk County Family Court order.”

The case is due back in court on Wednesday.