What is the prognosis for a patient with terminal cancer?
An accurate prognosis enables patients with terminal cancer to make plans, put their affairs in order, and decide how they want to spend the time they have left. A prognosis also may help the primary care physician refer the patient for hospice care at a time when the patient would most benefit from the service.
Traditionally, physicians have estimated prognosis using their clinical experience. A study1 of 196 patients with non–small cell lung cancer found that physicians were able to correctly predict the date of death within one month for only 10 percent of patients. However, they were able to correctly predict the date of death within three months for 59 percent of patients.1 Another study2 found that physicians usually overestimate survival.2 Physicians also commonly use the Karnofsky Performance Scale to predict the prognosis of a patient with terminal cancer. Using the Karnofsky Scale, a score of 50 percent or less in a patient with progressive underlying cancer predicts a median life expectancy of two months.3
Researchers have developed more objective and reproducible clinical rules to assist physicians in estimating prognosis. A systematic review4 identified 24 rules, of which only three were prospectively validated in a study group of patients who were not involved in the rules’ development. A search of recent literature did not identify any additional rules. Perhaps the best-validated clinical rule is the Palliative Prognosis Score (PPS). It was developed based on a study of over 500 Italian patients with terminal cancer who were admitted to 14 hospitals.5 The rule was prospectively validated in a second group of over 500 patients admitted to the same hospitals as the original group. In the validation group, the median age was 70 years; 56 percent had metastatic disease and 65 percent had locally advanced disease. The most common malignancies were lung (19 percent); colorectal (15 percent); stomach (12 percent); and pancreas, liver, or gallbladder (12 percent). Another group of researchers successfully validated the rule in 100 Australian patients with advanced cancer who were admitted to a palliative care unit and in 100 patients with advanced cancer who were admitted to an Australian teaching hospital.6 The PPS combines objective measures with the physician’s global estimate to predict a more accurate prognosis. Table 1 shows the PPS rule and its interpretation.
|Karnofsky Performance Scale (KPS) score of 10 to 20*||2.5|
|Clinical prediction of survival (weeks)|
|More than 12||0|
|11 to 12||2.0|
|7 to 10||2.5|
|5 to 6||4.5|
|3 to 4||6.0|
|1 to 2||8.5|
|Total white blood cell count|
|8,500 cells per mm3 or less (8.5 × 109 cells per L)||0|
|8,501 to 11,000 cells per mm3 (8.5 to 11 × 109 cells per L)||1.0|
|Greater than 11,000 cells per mm3||2.5|
|20 or greater||0|
|12.0 to 19.9||1.0|
|Less than 12 percent||2.5|
In previous validations of the PPS, scores were only determined by oncologists and palliative care specialists.5–7 Therefore, it should be used primarily by physicians with experience caring for patients who are older and who have a terminal illness. In addition, it is always important to remember that scores such as the PPS are meant to support decision making, not replace it. Rules should be used in the context of the physician’s knowledge of the patient.
Applying the Evidence
Your patient is a 63-year-old woman with terminal colon cancer who would like a more specific prognosis. She has some dyspnea and anorexia but is able to care for herself. Her white blood cell count is 4,000 cells per mm3 (4 × 109 cells per L) with 15 percent lymphocytes. You estimate that she will likely live approximately three or four months (i.e., more than 12 weeks).
Answer: Using the PPS, your patient receives 3.5 points (1 + 1.5 + 0 + 0 + 0 + 1), putting her in the low-risk group. She has a median survival of 76 days and an 87 percent likelihood of surviving at least one month.