Lung cancer targeted and immunotherapy: baseline tests and monitoring

On my morning walk, a simple question wouldn’t let go of me: if I were starting a modern treatment for lung cancer—whether a targeted pill or an immune checkpoint drug—what, exactly, should be checked first, and how would my care team keep an eye on me after that? The more I read, the more I realized that “baseline tests” and “monitoring” are the quiet choreography behind the scenes: lab work and scans that don’t make headlines but shape day-to-day decisions. Writing this down feels like packing a travel kit before a long road trip—half practical list, half pep talk to my future self to stay curious, ask questions, and notice patterns.

The moment I understood the point of baseline testing

For me it clicked when I pictured two overlapping maps. One map is the tumor’s biology: DNA changes that point to a matching targeted drug, or proteins like PD-L1 that hint whether immunotherapy is likely to help. The other map is my body’s starting line: how my liver, kidneys, thyroid, lungs, and heart are doing before a single dose. Put them together and you get a smarter plan. A high-value takeaway I wish I’d known earlier: the right baseline tests can prevent false alarms and avoidable interruptions later—especially with immune-related side effects that can mimic ordinary life. For a plain-English overview of immune-therapy side effects and how clinicians manage them, the ASCO guideline update is a solid anchor I keep coming back to here.

  • To choose a targeted drug, comprehensive biomarker testing is table stakes. The CAP/IASLC/AMP guidance explains what labs aim to detect and why that matters for therapy selection here.
  • For immunotherapy, clinicians also check baseline organ function and endocrine labs so there’s a reference if symptoms appear later. FDA labels for PD-1/PD-L1 drugs specifically call out monitoring for thyroid, liver, kidney, and glucose changes; an example is pembrolizumab’s label summarized here.
  • And it’s not just one-and-done. Baseline results guide the rhythm of follow-up—what to repeat monthly versus every few months, when to scan, and how to interpret “is this new?”

What goes on the baseline checklist I’d bring to clinic

Everyone’s situation is different, but these are the recurring items I saw across guidelines and clinic handouts, translated into the way I’d write them in a notebook. I imagine myself sliding this page across the table and saying, “Can we walk through these together?”

  • Biomarker testing on the tumor (tissue and/or liquid biopsy): EGFR, ALK, ROS1, BRAF V600E, MET exon 14 skipping, RET, NTRK, KRAS G12C, ERBB2/HER2 alterations, and PD-L1 expression. In oncogene-addicted disease, ESMO’s practice guideline lays out the landscape and why each target matters for first-line choices here.
  • Staging and baseline imaging: recent CT chest/abdomen/pelvis (or PET/CT when indicated) and a brain MRI in many advanced cases. This anchors future comparisons—so that anything new stands out instead of getting lost in guesswork.
  • Core labs before immunotherapy or targeted pills: complete blood count; comprehensive metabolic panel (with AST/ALT, bilirubin, creatinine); thyroid function (TSH ± free T4); fasting glucose or HbA1c; sometimes morning cortisol or ACTH if symptoms suggest endocrine issues. The ASCO immunotherapy toxicity guideline provides the rationale for these baseline values and periodic checks here.
  • Viral screening (per local policy and history): hepatitis B/C and HIV. It’s not universal, but clinicians often screen because certain therapies and steroids used for side-effect management can interact with chronic viral infections.
  • Cardiopulmonary snapshot: baseline ECG and electrolytes if a chosen targeted agent has QT-interval warnings; pulmonary status if there’s ILD risk or a history of radiation. These are pragmatic guardrails rather than red lines—my notes say “ask why it’s needed for my specific drug.”
  • Medication and autoimmune history: any baseline steroids, thyroid disease, diabetes, rheumatologic conditions, or transplants. These don’t automatically rule out modern therapy, but they shape the plan.

How I think about monitoring once treatment starts

When therapy begins, I picture two parallel tracks. One track is objective—the predictable cadence of labs and scans. The other is subjective—what my body is whispering between appointments. Both matter.

  • Lab rhythm: early on, labs are typically repeated every cycle or two. For checkpoint inhibitors, clinicians monitor liver enzymes, creatinine, and thyroid function at baseline and periodically—language echoed in FDA labels like pembrolizumab’s here and in guideline summaries such as NCCN’s immunotherapy toxicity resource here. If glucose creeps up, the team may check more often; if thyroid tests drift, they may add free T4 or antibodies.
  • Scan cadence: many teams scan around 6–12 weeks after starting, then adjust. One thing I didn’t appreciate at first is pseudoprogression—tumors may look bigger before they look better with immunotherapy. That’s where symptoms and lab trends help avoid knee-jerk decisions.
  • Targeted therapy specifics: depending on the drug class, clinicians may follow ECGs/electrolytes (QT-related agents), lipid panels (some TKIs), liver enzymes, or creatine kinase (if myalgias crop up). The ESMO oncogene-addicted NSCLC guidance provides class-level context on why these checks are common here.

Early signals I promised myself not to ignore

I keep a short, human-sized list on my phone. It’s easy to feel “I’m fine, it’ll pass,” but I’ve learned that checking in early usually means a shorter detour rather than a crisis later.

  • Lungs: new or worsening cough, chest tightness, or shortness of breath (think immune-related pneumonitis vs. infection). The ASCO guideline—again, my north star—spells out why timing and severity grading matter and how teams respond here.
  • Gut and liver: persistent diarrhea, abdominal pain, or dark urine—possible colitis or hepatitis. Baseline AST/ALT/bilirubin helps here; so do early stool or viral tests to rule out other causes.
  • Endocrine: unusual fatigue, cold or heat intolerance, headache with vision changes, dizziness, excessive thirst or urination—possible thyroid, pituitary, adrenal, or pancreatic (glucose) effects. I jot down even mild changes; they’re easier to sort out with trend lines.
  • Skin and joints: new rashes, severe itch, or joint swelling—uncomfortable but often very manageable when flagged early.

Simple frameworks that keep me grounded

When my mind starts spinning, I come back to three questions. They tamp down the noise and keep me engaged without trying to be my own doctor.

  • Step 1 Notice What is new since last visit? I compare against my own baseline—today’s symptoms versus week 0, today’s labs versus pre-treatment. I bring a one-page summary to avoid scrolling forever through portals.
  • Step 2 Compare Could this be treatment-related, disease-related, or something unrelated? Using guardrails from clinician-facing resources (NCCN’s toxicity pages are a good example to bookmark here), I try to articulate what makes me think A versus B.
  • Step 3 Confirm What’s the next small test that reduces uncertainty without overreacting? Maybe a repeat lab, a pulse oximeter check at home, or calling the on-call nurse if I’m unsure. I aim for clear notes: “If X worsens or Y shows up, I’ll call today.”

Targeted drugs versus immunotherapy in real life

On paper, targeted therapy looks tidy: find the driver, match the pill. Immunotherapy reads like a leap of faith: let the brakes off the immune system and see if it recognizes the cancer. In reality, both are methodical when the groundwork is done well.

  • Targeted therapy depends on detecting the right alteration. The CAP/IASLC/AMP guideline emphasizes assay quality and adequate samples so that actionable targets aren’t missed here. That’s why teams sometimes add a liquid biopsy at the start or at progression.
  • Immunotherapy often uses PD-L1 as a compass, though not a guarantee. Safety language in FDA labels makes it clear why baseline and periodic tests matter; pembrolizumab’s label is one illustration among many here.
  • Combination paths (chemo-immunotherapy or targeted plus targeted) exist too. ESMO’s guidance helps map those forks when multiple alterations or clinical factors compete for first place here.

Little habits I’m testing to make monitoring easier

Nothing fancy—just low-tech routines that make me a better partner to my clinicians.

  • I put lab and scan dates on a shared calendar and set reminders two days before, so I can ask for add-on tests if something new cropped up.
  • I keep a one-line-per-day symptom log. If I have a cough, I note when it’s worse (morning? exertion?), what helps, and whether there’s fever. Patterns beat anecdotes.
  • Before each visit, I draft three questions: “What’s my trend?” “What’s our threshold to re-image or repeat labs earlier?” “Is there anything I can track at home?”
  • When a drug has a known class effect (like thyroid changes on checkpoint inhibitors), I ask for the early-warning signs and what labs we’ll follow. Seeing the plan calms my brain.

When I hit the brakes and call sooner

There’s healthy stoicism and then there’s needless risk. I wrote myself a short “don’t be a hero” list for immune-related toxicities, with a promise to check in promptly. The ASCO guideline lays out graded management pathways that clinicians use in practice (worth a skim if you like to understand the why) here.

  • Sudden shortness of breath, oxygen saturation drop, or new chest pain
  • Watery diarrhea more than a few times a day, blood in stool, or severe abdominal pain
  • Severe fatigue with dizziness, headache with vision changes, or intolerable muscle weakness
  • Yellowing of the eyes/skin, dark urine, or severe itching with rash
  • Any symptom that is rapidly escalating or feels different from my usual baseline

What I’m keeping and what I’m letting go

I’m keeping three principles on a sticky note: map the biology (comprehensive biomarker testing up front), know your baseline (get the labs and scans that make future calls clearer), and trend, don’t guess (use repeated measurements and symptoms to guide next steps). For deeper dives, I bookmark one source for each angle: CAP/IASLC/AMP for the “what to test,” ESMO for where targets lead, NCCN and ASCO for “how to handle side effects,” and an FDA label for the exact, drug-specific safety language. It’s not about memorizing everything; it’s about knowing where to look when a fork in the road appears.

FAQ

1) Do I always need a liquid biopsy in addition to tissue testing?
Answer: Not always. Tissue remains the standard, but a liquid biopsy can help when tissue is scarce or when you want a faster read on circulating tumor DNA. The goal is comprehensive coverage of actionable targets so first-line choices are well-matched.

2) If my PD-L1 is low, does immunotherapy still make sense?
Answer: Possibly. PD-L1 is one compass, not a verdict. Some regimens combine immunotherapy with chemotherapy regardless of PD-L1 level, and clinical factors matter. Your team will weigh efficacy data, side-effect profiles, and your goals.

3) How often will I get scans after starting therapy?
Answer: Many teams re-image around 6–12 weeks after starting, then space out or adjust based on your response and symptoms. If something concerning arises, scans can happen sooner—having a clear baseline makes those comparisons meaningful.

4) Are immune-related side effects permanent?
Answer: Many are temporary and improve with prompt evaluation and treatment, but some can linger or require ongoing management. The key is early recognition and partnership with your clinicians; they follow graded pathways from guidelines to balance safety and treatment continuity.

5) Which baseline labs matter most before immunotherapy?
Answer: Typically thyroid function, liver enzymes, kidney function, and glucose get baseline checks, with repeats during treatment. Exact timing varies by regimen and your history. This isn’t a substitute for medical advice—treating teams tailor the plan to you.

Sources & References

This blog is a personal journal and for general information only. It is not a substitute for professional medical advice, diagnosis, or treatment, and it does not create a doctor–patient relationship. Always seek the advice of a licensed clinician for questions about your health. If you may be experiencing an emergency, call your local emergency number immediately (e.g., 911 [US], 119).