JOURNAL ARTICLE
REVIEW

Assessing tumor response to therapy

Wolfgang A Weber
Journal of Nuclear Medicine 2009, 50: 1S-10S
19380403
Most anticancer drugs are effective only in subgroups of patients, and our current understanding of tumor biology does not allow us to predict accurately which patient will benefit from a specific therapeutic regimen. Various techniques have, therefore, been developed for monitoring tumor response to therapy, but measuring tumor shrinkage on CT represents the current standard. Although response assessment on CT has been refined over many years, fundamental limitations remain. Interobserver variability in tumor size measurements is still high because of difficulties in delineating tumor tissue from secondary changes in the surrounding tissues. Furthermore, CT is inaccurate in differentiating viable tumor from necrotic or fibrotic tissue. Consequently, the degree of response may be underestimated on CT. Conversely, if tumor shrinkage is short lived and followed by rapid tumor regrowth, CT may overestimate the beneficial effects of a treatment. Finally, CT is limited in characterizing responses in tumors that do not change in size during therapy. Because the growth rate of untreated human tumors varies tremendously, an unchanged tumor size after some weeks of therapy may represent a drug effect but may also indicate a slowly growing tumor that was not affected by the applied therapy. Molecular imaging with PET and the glucose analogue (18)F-FDG PET has been shown to improve response assessment in several tumor types. In malignant lymphoma, international criteria for monitoring response to therapy have recently been revised, and the (18)F-FDG signal now plays a central role in defining tumor response. In a variety of solid tumors, single-center studies have indicated that (18)F-FDG PET may provide earlier or more accurate assessment of tumor response than CT, suggesting that (18)F-FDG PET could play a significant role in personalizing the treatment of malignant tumors. However, generally accepted criteria for response assessment in solid tumors are missing, which makes it frequently impossible to compare the results of different studies. International guidelines and criteria for response assessment by (18)F-FDG PET in solid tumors are, therefore, eagerly awaited.

Full Text Links

Find Full Text Links for this Article

Discussion

You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read
19380403
×

Save your favorite articles in one place with a free QxMD account.

×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"