taking a break

Hi There,
Well my sister is finally taking her trip with hubby and three children. She is leaving on Monday for two weeks. I'm concerned about the time she'll be off chemo and herceptin. Her Navelbine is generally given every week (2 weeks on and one week off) and herceptin weekly with no breaks. Yesterday was her "off week" for the Navelbine so she only had herceptin. Basically this means that she will be without Navelbine for 4 weeks and without Herceptin for 3 weeks. I was under the impression that she would at least get a three-week dose of Herceptin, but she didn't. Should we be concerned?...my sister isn't. I don't think she should be without everything for a long period of time, considering how serious her condition remains. I don't want to worry her so I haven't said anything, but I'm wondering if I should suggest that she get more Herceptin before she leaves on Monday. What are your thoughts? Has anyone taken such a break in the middle of treatment?