Cancer of the kidney refers to the uncontrolled growth of abnormal cells within the kidneys, which serve important role in removing waste products from the body. Early stage 1 renal cell cancers, defined as less than 7cm in size, are usually diagnosed incidentally, when patients undergo routine ultrasound or CT scans for health screening or other unrelated symptoms. In its early stages, kidney cancer usually does not cause any symptoms. As it progresses, it may cause visible blood in the urine, back pain, and weight loss. While some renal cell cancers are detected only after they have grown quite big, two-thirds of all kidney cancers are usually diagnosed before it spreads (metastasize) to the other organs such as the lung and the bony skeleton, through the bloodstream or the lymph vessels (Fig 1).
Figure 1: Stages of kidney cancer progression
The diagnosis of cancerous change is made based on the presence of features on the CT or MRI scan of the kidneys. When these tumours are surgically removed, 20% of such tumours will turn out to be benign, and do not need further follow-up.
Surgical removal of Stage 1 kidney tumours, whilst sparing the rest of the unaffected kidney, has now been established as the current international standard of care advocated by the European Association of Urology and American Urological Association. Such nephron-sparing surgery (NSS) is now preferred to radical nephrectomy, where the entire kidney is removed. Several large-scale studies have found that patients who undergo nephron-sparing surgery, live longer and have a significantly lower risk of developing hypertension, ischaemic heart disease or strokes over the long term compared to patients who had their entire kidney removed. In patients who have only one functioning kidney which undergoes cancerous change, NSS is the only means that offers such patients the possibility of avoiding renal failure and need for lifelong dialysis.
Nephron-sparing surgery is a technically more difficult operation than simply removing the entire kidney. As it involves removing the tumour from the kidney, there may be bleeding from the raw surfaces of the remaining kidney defect, or urine leakage around the kidney, which may result in postoperative infection and prolonged hospital stays. Thankfully, such complications are not common, the large majority of patients have an uneventful recovery, and NSS cancer outcomes are similar to radical nephrectomy.
Nephron-sparing surgery involves five main steps: (1) identify the tumour in the affected kidney; (2) clamp the blood vessels supplying the kidney to minimize bleeding; (3) remove the tumour with a 1cm rim of healthy tissue around it to avoid leaving cancer cells behind; (4) closing the defect left in the kidney tissue, and (5) removing the clamps off the blood vessels and checking for bleeding before closing up. (Fig 2).
Figure 2: Steps of nephron-sparing surgery for early kidney cancer
NSS may be performed through three approaches: (1) traditional open surgery, which involves a 15-20cm incision in the abdomen or flank; (2) laparoscopic surgery, which is performed through small incisions in the abdomen; or (3) robotic surgery, using the da Vinci® surgical robot to remove the tumour and sew up the resulting defect in the affected kidney. Minimally invasive surgery, with or without robotic instrumentation, offers many advantages over traditional open surgery – small incisions result in significantly less pain, much quicker recovery, shorter hospital stays and earlier return to daily activities. For open surgery, many patients complain of chronic pain or numbness over the large incision (Fig 3).
Fig 3(a): Patient with conventional open kidney surgery scar
Fig 3(b): Patient with minimally invasive nephron-sparing surgery scar.
In minimally invasive NSS, the surgical challenge lies in minimizing the clamp time on the vessels supplying the affected kidney. The longer the clamp time needed for excising the tumour and closing up the defect, the longer the kidney nephrons are starved of oxygen (known as warm ischaemia). Warm ischaemic clamp times of more than 30 minutes have been found to be associated with irreversible loss of kidney function. The enhanced clarity of vision and dexterity surgeons have using the da Vinci® robot to achieve the same goals of tumour excision and kidney reconstruction, significantly reduces the clamp time on the kidney vessels and the incidence of postoperative complications, compared with surgeons using conventional laparoscopic instruments. Several published studies now validate the superior results achieved with the robotic approach over laparoscopic and open surgery4 (Fig 4).
Fig 4: Repertoire of da Vinci® robotic instruments and their range of movement compared with the human wrist
With surgeons worldwide increasingly adopting robotic nephron-sparing surgery as their preferred mode of treatment, many centres have reported impressive outcomes for robotic NSS in dealing with such challenging cancers5. Such complex cancers previously deemed as too difficult for NSS to be performed safely, are no longer daunting for experienced robotic surgeons as the repertoire of surgical techniques for handling such scenarios continue to evolve. You should explore all available options by consulting surgeons with considerable expertise in dealing with such challenging cases.
Stage 1 kidney cancers carry a very good prognosis if they are removed early without having positive margins. In such patients, there is an 85-90% chance that at ten years after surgery, there will be no cancer recurrence. In healthy patients who have undergone successful nephron-sparing surgery of the affected kidney, their long-term quality of health is almost comparable to a patient of similar age with two healthy kidneys.
Early kidney cancers carry an excellent long-term prognosis if diagnosed and removed early. There is a 20% chance that such suspected cancers will turn out to be benign lesions. Kidney-sparing surgery has now become the standard of care for such early cancers. Where the surgical expertise is available, nephron-sparing surgery using the da Vinci® robot has been found to deliver the best surgical outcomes in terms of minimizing blood loss, warm ischaemia clamp times, and postoperative complications such as urine leaks. In this age of technological advances, patients should no longer have to lose their entire kidneys for such early tumours, particularly if these turn out to be benign on final analysis.