Last Christmas was a time of great mystery for a young Chinese man from Jakarta. For several months, this 33-year old Indonesian, Yackson, had noticed strange painful lumps appearing on the left side of his neck. He had also lost 8 kilograms of weight.

He saw several local doctors but decided to go to Penang as things did not improve despite medication. When the possibility cancer was raised, he called home and got a referral from his relatives to head down to Singapore to see me.

When I examined him, I found  chains of enlarged lymph nodes on the both sides of his neck, but more extensive on the left side. These lymph nodes were discrete, rubbery and tender. The largest node was about 3 cm in size. In addition, there was also a mass that could be felt in his abdomen.

With clinical findings of enlarged lymph nodes and weight loss in a young man, my provisional diagnosis was malignant lymphoma (primary cancer of the lymph nodes).

“Easy-peasy,” I thought to myself as I ordered a series of blood tests and arranged for a PET-CT scan to be followed by a core biopsy of the lymph nodes.

That same day, the PET-CT scan was done and the radiologist reported “extensive hypermetabolic nodes on both sides of the diaphragm consistent with lymphoma”.  Besides the affected lymph nodes, the entire liver was studded with tumors and there was extensive spread to the bones all over his body.

“Right again!” I thought.

The next day, when the patient came back for his review, I called up the pathologist, a close colleague, only to be told that it was definitely not a lymphoma. He was certain that it was a cancer but the cells were so abnormal, that despite extensive studies, he could not sub-type it further.

The final diagnosis was poorly differentiated carcinoma.

The blood tests were not of any help as the cancer markers were normal. His liver function tests were deranged because of the cancer spread to the liver. I even tested him for AIDS and carried out an ultrasound of his testicles (just in case the cancer was hiding there) but both tests came back normal.

“So doctor, where did my cancer come from?” Yackson asked perceptively after I went through all the test results.

I had to tell him honestly that we don’t know. Despite all the investigations, we did not know where the tumor originated from, nor could we classify the type of cancer cells. As for treatment, it was obvious that surgery and radiotherapy were out of the question and that his only option was to have chemotherapy.

On a broad level, treating cancer is actually quite easy. The three things we need to know are the type of cancer cell, the organ of origin and the extent of disease involvement.

In this patient, we only knew that he is very advanced disease but had no clue about  the origin or the type of cell (except that it was definitely a cancer).

According to the medical literature, between two to four per cent of all cancer patients have a cancer whose primary site is never found. These patients are classified as “cancers of unknown primary” (CUP).

Besides the lumps in his neck and weight loss, he had no other localizing symptoms. There was no nosebleed, ringing in the ear or deafness to suggest a cancer of the nose.  There was no abdominal symptoms such as pain, change in bowel habits of blood in the stools to suggest a cancer of the gastro-intestinal system.

The biggest challenge is what drugs to use for treating such patients.

Most oncologists have their own favorite treatment regimens for treating patients with CUP. With more than two decades of experience, I too had a trick or two.

“Don’t worry. I’ll take care you!” I said, trying to sound confident – after all, this was a young man who had seen me conducting test after test, but failing to uncover what cancer he had. Somehow, I felt telling him that it was “CUP” was not going to look very impressive.

With that, we embarked on the journey and never looked back.

After one cycle of chemotherapy, the painful lumps started to regress in size and his appetite improved. After three cycles of chemotherapy, the PET-CT reported that all the lymph nodes, the nodules in the liver and bone lesions had resolved. He went on to complete six cycles of chemotherapy.

If I saw a similar patient today, I would probably try the same magic potion again and hope for best.

But what a difference a year makes in medical science. Since that time, I have been made aware of a US laboratory called Champions Oncology. This company has been successful in growing patient’s cancer in nude mice (these are specially-bred, immuno-compromised mice with no ability to reject the cancer).

This allows testing of various chemotherapy drugs and targeted agents on these mice to help select the most active treatments for the patient.

The preliminary results suggested good correlation in treatment response between what is seen in the patient as demonstrated in the mice.

If so, we can use the results from the mice models to select the “best treatment” for the patients.

Yackson came back for his follow-up review recently. The PET-CT continued to show all clear. In my mind, I know that his cancer will eventually relapse.

What should I offer him as salvage therapy when the disease recurs? If only I had his tumour growing in a nude mouse, I wouldn’t have to shoot in the dark.