Fever During Chemo: What to Know

There is no single fever threshold in cancer care, and it helps to know that before you find two on your fridge.

NCI's patient page on infection tells people to call for a temperature of 100.4 F (38 C) or higher. The clinical definition used in hospitals is different: a single oral reading of 101 F (38.3 C) or higher, or a reading of 100.4 F (38 C) or higher that lasts at least an hour, in a person whose absolute neutrophil count is under 1,500 cells per microliter.

Many US infusion centers hand out 100.4 F as the call threshold, because it is the lowest of the three and the safest to act on. If your team wrote a different number on your card, use theirs. If nobody gave you a number, use 100.4 F and call.

One rule cuts across all of them: do not take acetaminophen or ibuprofen to bring a temperature down before you call. They work, and that is the problem. A masked fever delays the call, and delay is what causes harm here.

Neutrophils are the white cells that swallow bacteria. Chemotherapy suppresses the marrow, so their number falls and then recovers each cycle.

Your absolute neutrophil count, the ANC, is calculated from your blood count:

ANC = white blood cell count x (percent neutrophils plus percent bands) divided by 100.

The thresholds that matter:

• Under 1,500 per microliter: neutropenia.
• Under 500: severe neutropenia.
• Under 100: profound neutropenia, where the risk of bacteria in the bloodstream is highest.

Ask your team when your nadir is, meaning the day your count is expected to be lowest. For most standard regimens it falls somewhere in the second week after a dose. Knowing your nadir date tells you which days deserve the most vigilance.

Without neutrophils, an infection has very little standing in its way. The usual signs of infection are also blunted, because pus, redness, and swelling are made largely of neutrophils. So a person can have a serious bloodstream infection while looking mildly unwell.

That is why fever with neutropenia gets treated as a time-critical emergency. For high-risk patients, guidance is intravenous antibiotics within 1 hour of triage, not after the results come back.

The sequence is fairly standard, and knowing it makes the visit less bewildering.

Blood cultures are drawn first, from a vein in the arm and separately from any central line or port, along with samples from any suspicious site. Then antibiotics start immediately, without waiting for those cultures.

The Infectious Diseases Society of America recommends starting with a single antibiotic that covers Pseudomonas, a bacterium that is dangerous in this setting. Cefepime, ceftazidime, piperacillin with tazobactam, meropenem and imipenem-cilastatin are the drugs usually reached for. Which one, and how much, is worked out by the hospital team from your kidney function, your allergies and what organisms circulate locally, so there is no standard amount to expect.

Vancomycin is deliberately not part of the first round. It is added if a line infection, a skin or soft tissue infection, pneumonia, or unstable blood pressure is suspected. If there is no response, coverage widens to resistant organisms such as MRSA.

There are formal scores that separate low-risk from high-risk patients, and they explain why two people with the same temperature get different plans.

The MASCC index scores out of 26. A score above 21 is low risk; a score below 21 is high risk. Points come from how ill you look, having a systolic blood pressure above 90, no COPD, having a solid tumor rather than a blood cancer with prior fungal infection, no dehydration, being an outpatient when the fever started, and being under 60.

For carefully selected low-risk patients, tablets at home are an option. Ciprofloxacin paired with amoxicillin-clavulanate is the usual pairing, and a different partner drug is chosen where penicillin is not an option. If you are sent home on tablets, take them exactly as your own prescription is written and finish the course. A fever that is still there after two or three days on them means going back in.

CISNE is a second score, designed specifically for use in emergency departments to identify who is truly low risk.

If you are sent home, expect at least 4 hours of observation first.

• Your temperature, the time you took it, and how (oral is what the thresholds refer to).
• The name of your chemotherapy regimen and the date of your last dose.
• Your most recent blood count, if you have it, and whether you had a growth factor shot.
• Whether you have a port or PICC line.
• Any antibiotic allergies.
• Other symptoms: chills, cough, burning on urination, diarrhea, sore mouth, redness around a line site.
• Who is driving you, since you may be admitted.

• Your temperature reaches your team's threshold, or 100.4 F (38 C) if you were not given one.
• Shaking chills, even with a normal temperature.
• Confusion, unusual drowsiness, or a new stiff neck.
• Breathing hard, or a new cough with breathlessness.
• Redness, pain, or discharge around a port or PICC line.
• Dizziness on standing, or passing very little urine.
• Any fever within a week of your expected nadir date.

Say the words "I am on chemotherapy and I may be neutropenic" at the desk. That phrase moves you up the triage queue.

Low White Blood Cells During Chemotherapy, Neutropenia During Chemotherapy, Neutropenic Fever During Cancer Treatment, and Chemotherapy.

• https://www.cancer.gov/about-cancer/treatment/side-effects/infection
• https://www.ncbi.nlm.nih.gov/books/NBK541102/