London, Oct 18 (IANS): A lung cancer patient in her 80s, who rejected conventional treatment and self-medicated with cannabidiol ('CBD') oil saw her tumour shrink, said doctors in a study published in the journal in BMJ Case Reports.

The case suggests the need to explore the use of cannabidiol ('CBD') oil as a potential lung cancer treatment.

In the paper, doctors at the Respiratory Department, at Watford General Hospital in the UK wrote that the woman was diagnosed with non-small cell lung cancer in 2018 and her tumour was 41 mm in size.

In addition, the woman was a chain smoker, and also had mild chronic obstructive pulmonary disease (COPD), osteoarthritis, and high blood pressure, for which she was taking various drugs.

But as the tumour showed no evidence of local or further spread, she was suitable for conventional treatment of surgery, chemotherapy, and radiotherapy.

However, the woman refused treatment and shortly after her original diagnosis, she started using the CBD oil -- 0.5 ml of the oil, usually three times a day, but sometimes twice --on the advice of a relative since August 2018.

Regular CT scans every 3-6 months showed her tumour progressively shrinking in size from 41 mm in June 2018 to 10 mm by February 2021, equalling to an overall 76 per cent reduction in maximum diametre, averaging 2.4 per cent a month.

"Without the knowledge of her clinicians, she chose to self-administer 'cannabidiol (CBD) oil' orally 2-3 times daily," the doctors wrote in the paper.

"Serial imaging showed that her cancer reduced in size progressively from 41 mm to 10 mm over a period of 2.5 years," they added.

The woman told doctors that the supplier advised that hot food or drinks should be avoided when taking the oil as she might otherwise feel stoned. The woman said she had reduced appetite since taking the oil but had no other obvious 'side effects'. There were no other changes to her prescribed meds, diet, or lifestyle. And she continued to smoke throughout.

This is just one case report, with only one other similar case reported, caution the authors. And it's not clear which of the CBD oil ingredients might have been helpful, the doctors said.

"Although there appears to be a relationship between the intake of CBD oil and the observed tumour regression, we are unable to conclusively confirm that the tumour regression is due to the patient taking CBD oil," they pointed out.

"More research is needed to identify the actual mechanism of action, administration pathways, safe dosages, its effects on different types of cancer and any potential adverse side effects when using cannabinoids," they noted.